Øyvind Erik Næss

• Tesli, Martin Steen; Hjellvik, Vidar; Lergenmuller, Simon; Hjell, Gabriela; Jangmo, Andreas & Haram, Marit [Show all 13 contributors for this article] (2026). Socioeconomic Position and Somatic Comorbidity in Mental Disorders. Acta Psychiatrica Scandinavica. ISSN 0001-690X. doi: 10.1111/acps.70113. Full text in Research Archive Show summary

  Introduction Individuals with mental disorders face an elevated risk for somatic noncommunicable diseases (NCD), such as cardiovascular disease (CVDs), chronic obstructive pulmonary disease (COPD), diabetes, and cancer. Low socioeconomic position (SEP) is linked to both mental disorders and somatic NCDs, but its role in this association remains unclear. Here, we provide a comprehensive overview of how associations between mental disorders and somatic NCDs vary by SEP indicators. Methods Data on all adult individuals resident in Norway from 01.01.2008 to 01.01.2010 (N = 3,589,719) were derived from a nationwide registry linkage including information on primary and secondary health care, dispensed drugs, causes of death, and socioeconomic factors. We assessed four broad types of mental disorders (psychotic, bipolar, depressive and anxiety disorders) and four categories of somatic NCDs (CVD, COPD, diabetes, cancer) diagnosed during follow-up from 01.01.2010 to 31.12.2020. Educational attainment and household income were used as SEP indicators, in addition to parental educational attainment. Cox regression models estimated hazard ratios for somatic NCDs among individuals with mental disorders compared to the general population, adjusting for and stratifying by SEP, sex, and age. Results All mental disorders were associated with an increased risk of somatic NCDs, strongest for COPD and weakest for cancer. Risk increased with disorder severity, with psychotic and bipolar disorders showing the strongest associations. Young adults with psychosis had a 4–5-fold increased risk of diabetes and COPD. Low SEP was associated with both mental disorders and somatic NCDs with moderate attenuating effects in their co-occurrence and little variation across SEP strata. Conclusion We found an increased risk of somatic NCDs in individuals with mental disorders and identified young adults with psychosis as a particularly vulnerable subgroup. Low SEP compounds this burden, underscoring the need for integrated mental and somatic healthcare strategies.

• Eide, Helena Niemi; Håberg, Siri Eldevik; Næss, Øyvind Erik; Stephansson, Olof & Magnus, Maria Christine (2026). COVID-19 mRNA Vaccination in Pregnancy and Risk of Infection in Early Childhood. Pediatrics. ISSN 0031-4005. 157(4), p. 1–9. doi: 10.1542/peds.2025-073661. Full text in Research Archive Show summary

  OBJECTIVE To examine associations between COVID-19 vaccination during pregnancy and the risk of various infections in early childhood. METHODS We conducted a nationwide, register-based cohort study comprising all live-born infants in Norway between March 2021 and December 2023 with follow-up through 2023. We used Cox regression to estimate hazard ratios for infections diagnosed in primary or specialist health care. Separate analyses were performed for specific infections, including COVID-19. RESULTS Among 146 031 infants born in Norway in the study period, 37 013 (25%) were exposed to COVID-19 vaccination in pregnancy. There was no difference in the overall risk of any infection registered in specialist care among offspring exposed to maternal vaccination (adjusted hazard ratio [HR], 0.99; 95% CI, 0.95–1.03). A slightly increased risk of being registered with any infection in primary care was observed among exposed offspring (adjusted HR, 1.05; 95% CI, 1.03–1.07), which was fully attenuated after excluding children of mothers who remained unvaccinated at the end of follow-up. The offspring’s protection against COVID-19 decreased over time, and the adjusted HRs for hospital contact were 0.48 for the first 2 months (95% CI, 0.40–0.56), 0.76 at 3 to 5 months (95% CI, 0.60–0.98), 1.13 at 6 to 11 months (95% CI, 0.82–1.56), and 1.14 after 12 months (95% CI, 0.72–1.79). No notable difference in the risk of hospital contacts for infections other than COVID-19 was observed. CONCLUSION COVID-19 vaccination during pregnancy protects the offspring against hospital contact for COVID-19 during the first 6 months of life. No apparent effect was observed for other infections.

• Næss, Øyvind Erik & Nguyen, Huong Thu (2026). Unobserved individual-level variation in cardiovascular mortality in birth cohorts born before and after 1945. BMC Cardiovascular Disorders. doi: 10.1186/s12872-026-05552-y. Full text in Research Archive
• Asefa, Henok; Brustad, Hilde Kjelgaard; Næss, Øyvind Erik; Thelle, Dag S & Holst, Rene (2025). On modeling the shared environment. American Journal of Epidemiology. ISSN 0002-9262. p. 1–8. doi: 10.1093/aje/kwaf255. Full text in Research Archive Show summary

  Abstract The shared environment is a key component in estimating the heritability of phenotypic traits from familial data. Unlike the genetic components, defined by the kinship parameters, the shared environment stems from complex, latent processes that vary in nature and impact across traits. This concept is intricate, encompassing latent variables and ambiguous interpretations that differ across scientific disciplines. A common approach assumes a 100% correlation for the shared environment among all family members. However, this model has inherent limitations and may fail to capture the dynamics of the conditions that constitute the shared environment within and across traits. This study explores aspects of the shared environment and adopts a more general approach to modeling its correlation structure. We introduce models that represent different dynamic structures, enabling alternative interpretations of shared environmental influence on the transmission of phenotypic traits. A more realistic correlation structure for the shared environment will result in more accurate and precise heritability estimates for a given trait, as well as deeper understanding of its etiology. We demonstrate the performance of our proposed models through simulations and application to data on body mass index and systolic blood pressure from Norwegian health surveys linked to family data.

• Jones, Paul Remy; Bhatta, Laxmi; Howe, Laurence J.; Veloz, Maria Fernanda Vinueza; Davies, Neil Martin & Smith, George Davey [Show all 8 contributors for this article] (2025). Education and cardiovascular disease: A within-family Mendelian randomization analysis. International Journal of Epidemiology. ISSN 0300-5771. 54(5). doi: 10.1093/ije/dyaf144. Full text in Research Archive Show summary

  Background: Observational studies have consistently found educational inequalities in cardiovascular disease (CVD) risk. Mendelian randomization (MR) analyses have suggested a direct causal effect of education; however, estimates may be biased by demography or dynastic effects. This study aimed to estimate the effects of educational attainment on CVD risk and serum lipid concentrations before and after accounting for family structure. Methods: This study included 26 961 siblings from the Trøndelag Health Study (HUNT) and 23 640 siblings from UK Biobank, and used data on >120 000 individuals, predominantly of European ancestry, from a recent international within-sibship genome-wide association study. The exposure was educational attainment. The outcomes were CVD risk and serum concentrations of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides. Standard and within-sibship MR analyses were used. Results: In the summary data analysis, there was a 6% lower risk of CVD [odds ratio (OR) 0.94, 95% confidence interval (CI) 0.92 to 0.96] for each additional standard deviation of liability to educational attainment. This was consistent having accounted for family structure (OR 0.96, 95% CI 0.91 to 1.01). Educational attainment was also beneficially associated with each serum lipid concentration both before and after accounting for family structure. Results were broadly similar in the individual participant analysis. Conclusion: There is a protective effect of educational attainment on CVD risk and a beneficial effect on serum lipid concentrations not due to familial factors shared by siblings, suggesting that increasing education may be beneficial for cardiovascular health.

• Veloz, Maria Fernanda Vinueza; Bhatta, Laxmi; Jones, Paul Remy; Tesli, Martin Steen; Smith, George Davey & Davies, Neil Martin [Show all 8 contributors for this article] (2025). Educational attainment and mental health outcomes: A within-sibship Mendelian randomization study. Psychological Medicine. ISSN 0033-2917. 55, p. 1–10. doi: 10.1017/s0033291725101736. Full text in Research Archive Show summary

  Abstract Background Observational studies indicate that higher educational attainment (EA) is associated with a lower risk of many mental health conditions (MHC). We assessed to what extent this association is influenced by genetic nurture and demographic factors (i.e., assortative mating and population structure). Methods We conducted a within-sibship Mendelian randomization (MR) study. The sample consisted of 61 880 siblings (27 507 sibships) from the Trøndelag Health Study-HUNT (Norway) and UK Biobank (United Kingdom). MHC outcomes included symptom scores for anxiety, depression, and neuroticism, measured using the Hospital Anxiety and Depression Scale, the 7-item Generalized Anxiety Disorder Scale, the 9-item Patient Health Questionnaire, and the Eysenck Personality Questionnaire, along with self-reported psychotropic medication use. Results One standard deviation (SD) increase in liability to EA was associated with lower anxiety (−0.20 SD [95% CI: −0.26, −0.14]), depression (−0.11 SD [−0.43, −0.22]), and neuroticism scores (−0.30 SD [−0.53, −0.06]), as well as lower odds of psychotropic medication use (OR: 0.60 [0.52, 0.69]). Within-sibship MR estimates remained consistent with population-based estimates: anxiety (−0.17 SD [−0.33, −0.00]); depression (−0.18 SD [−1.26, 0.89]); neuroticism (−0.29 SD [−0.43, −0.15]); psychotropic medication use (OR, 0.52 [0.34, 0.82]). Conclusions Higher EA or genetic liability to education reduces symptoms of anxiety, neuroticism, and psychotropic medication use. These mental health benefits do not seem to be explained by EA-linked genetic nurture or demographic factors. Regarding depression, results were less conclusive due to imprecise estimates, though beneficial effects of genetic liability to higher EA are possible and warrant further investigation.

• Nguyen, Huong Thu; Ystrøm, Eivind; Gjerde, Line Cecilie & Næss, Øyvind Erik (2025). Life course socioeconomic position and the risk of cardiovascular events and all-cause mortality in a Norwegian twin study. Scientific Reports. 15. doi: 10.1038/s41598-025-16975-6. Full text in Research Archive
• Nguyen, Huong Thu; Kjøllesdal, Marte Karoline Råberg; Choi, Hye Jung; Veloz, Maria Fernanda Vinueza & Næss, Øyvind Erik (2025). Quantifying the dose-response relationship between childhood family education levels and cardiovascular disease risk. Public Health. ISSN 0033-3506. 247. doi: 10.1016/j.puhe.2025.105849. Full text in Research Archive
• Veloz, Maria Fernanda Vinueza; Kjøllesdal, Marte Karoline Råberg; Nguyen, Huong Thu; Carslake, David & Næss, Øyvind Erik (2025). Cognitive ability in offspring conscripts and cardiovascular disease risk in extended family members: assessing the impact of modifiable risk factors on familial risk. Journal of Epidemiology and Community Health. ISSN 0143-005X. 79(8), p. 631–637. doi: 10.1136/jech-2024-222599. Full text in Research Archive
• Nguyen, Huong Thu; Moger, Tron Anders; Valberg, Morten; Degerud, Eirik; Page, Christian Magnus & Leblanc, Marissa [Show all 7 contributors for this article] (2024). Individual heterogeneity, educational attainment and cardiovascular mortality: a pooled analysis of Norwegian health surveys. BMJ Public Health. 2. doi: 10.1136/bmjph-2023-000104. Full text in Research Archive Show summary

  Background: Smoking, physical inactivity, cholesterol level and systolic blood pressure are well-established risk factors for cardiovascular diseases (CVD). However, even among individuals with similar levels of these factors, a substantial degree of variation in risk may still remain. We investigated the variation in this unexplained risk across educational levels. Methods: The study population (N=451 800) was from Norwegian health surveys and linked to the National Education Database and the Norwegian Cause of Death Registry. We used survival analysis with frailty models to measure unobserved heterogeneity (frailty variation). Models were stratified by three educational levels. We highlight the degree of heterogeneity by presenting Gini coefficients and indicate how much the unobserved heterogeneity differed across levels of education from the estimated parameters of the frailty distributions. Lorenz curves were plotted for a graphical representation of inequalities in individual risk. Main results: The estimated frailty variances were 24.96, 34.12 and 42.37 in the low, middle and high education groups, respectively, before adjusting for risk factors and 3.76, 7.12 and 7.82 after adjusting for risk factors. The corresponding Gini coefficients were 0.75, 0.84 and 0.86 for low, middle and high education groups, respectively. Conclusion: A large share of the variation in CVD mortality was explained by the observed risk factors. However, a substantial individual unobserved variation in CVD mortality remained after adjusting for these risk factors. Our findings indicate that the unobserved variation in CVD mortality could vary somewhat between educational groups, but that education does not explain the major share of the remaining substantial heterogeneity.

• Skåra, Karoline Hansen; Lee, Yunsung; Jugessur, Astanand; Gjessing, Håkon K.; AVIV, Abraham & Brumpton, Ben Michael [Show all 11 contributors for this article] (2024). Telomere length in relation to fecundability and use of assisted reproductive technologies: the Norwegian Mother, Father, and Child Cohort Study. Research Square. ISSN 2693-5015. doi: 10.21203/rs.3.rs-4430021/v1. Full text in Research Archive
• Skåra, Karoline Hansen; Camba, Alvaro Hernaez; Næss, Øyvind Erik; Fraser, Abigail; Lawlor, Deborah A. & Burgess, Stephen [Show all 8 contributors for this article] (2024). Cardiovascular disease risk factors and infertility: multivariable analyses and one-sample Mendelian randomization analyses in the Trøndelag Health Study. Human Reproduction Open. 2024(3). doi: 10.1093/hropen/hoae033. Full text in Research Archive Show summary

  STUDY QUESTION: Are cardiovascular disease (CVD) risk factors causally associated with higher risk of infertility among women and men? SUMMARY ANSWER: We found evidence to support a causal relationship between smoking initiation and history of infertility in women. WHAT IS KNOWN ALREADY: Several CVD risk factors are associated with history of infertility. Previous studies using Mendelian randomization (MR) further support a causal relationship between BMI and infertility in women. STUDY DESIGN, SIZE, DURATION: We used data from the Trøndelag Health Study (HUNT) in Norway, a prospective population-based cohort study, including 26 811 women and 15 598 men participating in three survey collections in 1995–1997 (HUNT2), 2006–2008 (HUNT3), and 2017–2019 (HUNT4). PARTICIPANTS/MATERIALS, SETTING, METHODS: Our outcome was women’s self-reported history of infertility, defined as ever having tried to conceive for 12 months or more or having used ART. We assigned the history of infertility reported by women to their male partners; therefore, the measure of infertility was on the couple level. We used both conventional multivariable analyses and one-sample MR analyses to evaluate the association between female and male CVD risk factors (including BMI, blood pressure, lipid profile measurements, and smoking behaviours) and history of infertility in women and men, separately. MAIN RESULTS AND THE ROLE OF CHANCE: A total of 4702 women (18%) and 2508 men (16%) were classified with a history of infertility. We found a higher risk of infertility among female smokers compared to non-smokers in both multivariable and MR analyses (odds ratio (OR) in multivariable analysis, 1.20; 95% CI, 1.12–1.28; OR in MR analysis, 1.13; CI, 1.02–1.26), and potentially for higher BMI (OR in multivariable analysis, 1.13; CI, 1.09–1.18; OR in MR analysis, 1.11, CI, 0.92–1.34). In multivariable analysis in women, we also found evidence of associations between triglyceride levels, high-density lipoprotein cholesterol, lifetime smoking index, and smoking intensity with higher risk of infertility. However, these results were not consistent in MR analyses. We found no robust or consistent associations between male CVD risk factors and infertility. LIMITATIONS, REASONS FOR CAUTION: Our main limitation was that the CVD risk factors measured might not adequately capture the relevant time periods for when couples were trying to conceive. Additionally, we did not have information on causes of infertility in either women or men. WIDER IMPLICATIONS OF THE FINDINGS: Women with infertility could have a worse CVD risk factor profile and thus public health interventions aimed at reducing the impact of some CVD risk factors, such as smoking and BMI, could reduce the burden of infertility. However, additional MR studies of the relationship between CVD risk factors and infertility with a larger sample size would be of value. STUDY FUNDING/COMPETING INTEREST(S): The study was supported by a grant from the European Research Council under the European Union’s Horizon 2020 research and innovation program (grant agreements no. 947684). This research was also supported by the Research Council of Norway through its Centres of Excellence funding scheme (project no. 262700) and partly funded by the Research Council of Norway, project: Women’s fertility—an essential component of health and well-being (project no. 320656). D.A.L. and A.F. work in a unit that is supported by the University of Bristol and the UK Medical Research Council (MC_UU_00011/6). D.A.L.’s contribution to the article is supported by the European Research Council (101021566), the British Heart Foundation (CH/F/20/90003 and AA/18/7/34219). S.B.’s contribution to the article is supported by the Wellcome Trust (225790/Z/22/Z). B.M.B. is funded by The Liaison Committee for education, research and innovation in Central Norway; and the Joint Research Committee between St. Olavs Hospital and the Faculty of Medicine and Health Sciences, NTNU. The genotyping in HUNT was financed by the National Institute of Health (NIH); University of Michigan; The Research Council of Norway; The Liaison Committee for education, research and innovation in Central Norway; and the Joint Research Committee between St. Olavs Hospital and the Faculty of Medicine and Health Sciences, NTNU. None of the funding organizations influenced the study design, reporting, or interpretation of results. The views expressed in the present article are those of the authors and not necessarily any acknowledged funding organization. D.A.L. reports grants from Medtronic Ltd and Roche Diagnostics outside the submitted work. The other authors have no conflicts of interest.

• Camba, Alvaro Hernaez; Skåra, Karoline Hansen; Page, Christian Magnus; Mitter, Vera R.; Hernández, Marta H. & Magnus, Per Minor [Show all 16 contributors for this article] (2024). Parental genetically predicted liability for coronary heart disease and risk of adverse pregnancy outcomes: a cohort study. BMC Medicine. 22. doi: 10.1186/s12916-023-03223-9. Full text in Research Archive Show summary

  Background Adverse pregnancy outcomes (APO) may unmask or exacerbate a woman’s underlying risk for coronary heart disease (CHD). We estimated associations of maternal and paternal genetically predicted liability for CHD with lifelong risk of APOs. We hypothesized that associations would be found for women, but not their male partners (negative controls). Methods We studied up to 83,969‬ women (and up to 55,568‬ male partners) from the Norwegian Mother, Father and Child Cohort Study or the Trøndelag Health Study with genotyping data and lifetime history of any APO in their pregnancies (1967–2019) in the Medical Birth Registry of Norway (miscarriage, stillbirth, hypertensive disorders of pregnancy, gestational diabetes, small for gestational age, large for gestational age, and spontaneous preterm birth). Maternal and paternal genetic risk scores (GRS) for CHD were generated using 148 gene variants (p-value < 5 × 10−8, not in linkage disequilibrium). Associations between GRS for CHD and each APO were determined using logistic regression, adjusting for genomic principal components, in each cohort separately, and combined using fixed effects meta-analysis. Results One standard deviation higher GRS for CHD in women was related to increased risk of any hypertensive disorders of pregnancy (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.05–1.10), pre-eclampsia (OR 1.08, 95% CI 1.05–1.11), and small for gestational age (OR 1.04, 95% CI 1.01–1.06). Imprecise associations with lower odds of large for gestational age (OR 0.98, 95% CI 0.96–1.00) and higher odds of stillbirth (OR 1.04, 95% CI 0.98–1.11) were suggested. These findings remained consistent after adjusting for number of total pregnancies and the male partners’ GRS and restricting analyses to stable couples. Associations for other APOs were close to the null. There was weak evidence of an association of paternal genetically predicted liability for CHD with spontaneous preterm birth in female partners (OR 1.02, 95% CI 0.99–1.05), but not with other APOs. Conclusions Hypertensive disorders of pregnancy, small for gestational age, and stillbirth may unmask women with a genetically predicted propensity for CHD. The association of paternal genetically predicted CHD risk with spontaneous preterm birth in female partners needs further exploration.

• Skåra, Karoline Hansen; Lee, Yunsung; Jugessur, Astanand; Gjessing, Håkon K.; Aviv, Abraham & Brumpton, Ben Michael [Show all 11 contributors for this article] (2024). Telomere length in relation to fecundability and use of assisted reproductive technologies: the Norwegian Mother, Father, and Child Cohort Study. BMC Medicine. 22(1). doi: 10.1186/s12916-024-03795-0. Full text in Research Archive Show summary

  Background: Telomere length (TL) has been reported to be associated with conditions such as endometriosis and polycystic ovary syndrome, with some studies finding associations with shorter TL and others with longer TL. In men, studies mostly report associations between shorter TL and sperm quality. To our knowledge, no studies have thus far investigated associations between TL and fecundability or the use of assisted reproductive technologies (ART). Methods: This study is based on the Norwegian Mother, Father, and Child Cohort (MoBa) Study and uses data from the Medical Birth Registry of Norway (MBRN). We included women (24,645 with genotype data and 1054 with TL measurements) and men (18,339 with genotype data and 965 with TL measurements) participating between 1998 and 2008. We investigated associations between leukocyte TL (LTL) and fecundability (defined as the probability to conceive within a given menstrual cycle), infertility (defined has having spent 12 months or more trying to conceive without success), and ART use. We also repeated the analyses using instrumental variables for LTL consisting of genetic risk scores for LTL and genetically predicted LTL. Results: Approximately 11% of couples had experienced infertility and 4% had used ART. LTL was not associated with fecundability in women (fecundability ratio [FR], 0.98; 95% confidence interval [CI], 0.92–1.04) or men (FR, 0.99; CI, 0.93–1.06), nor with infertility in women (odds ratio [OR], 1.03; CI, 0.85–1.24) or men (OR, 1.05; CI, 0.87–1.28). We observed an increased likelihood of using ART with increasing LTL in men (OR, 1.22; CI, 1.03–1.46), but not in women (OR, 1.10; CI, 0.92–1.31). No significant associations were observed using the instrumental variables for LTL. Conclusions: We found no indication that LTL is a suitable biomarker for assessing fecundability, infertility, or ART use. Additional studies are required to replicate the association observed between LTL and ART use in men.

• Choi, Hye Jung; Leblanc, Marissa Erin; Moger, Tron Anders; Valberg, Morten; Page, Christian Magnus & Aamodt, Geir [Show all 7 contributors for this article] (2023). Geographical variation in cardiovascular disease mortality in Norway: The role of life course socioeconomic position and parental health. Health and Place. ISSN 1353-8292. 83. doi: 10.1016/j.healthplace.2023.103095. Full text in Research Archive Show summary

  Despite substantial geographical variation in cardiovascular (CVD) mortality within countries, little is known about whether this variation can be explained by individuals' life course socioeconomic position (SEP) or differences in family history of premature CVD deaths. Cox proportional hazards models were used to investigate the association between the county of residence at ages 50–59 and CVD death in Norwegians born between 1940 and 1959 and survived to at least age 60, using national data. Individual life course SEP and family history of premature CVD death reduced the geographical variation in CVD mortality across Norwegian counties, but some significant differences remained. Furthermore, CVD risk varied by residents' migration histories between two counties with distinct CVD and socioeconomic profiles.

• Howe, Laurence J; Rasheed, Humaira; Jones, Paul Remy; Boomsma, Dorret I; Evans, David M & Giannelis, Alexandros [Show all 45 contributors for this article] (2023). Educational attainment, health outcomes and mortality: a within-sibship Mendelian randomization study. International Journal of Epidemiology. ISSN 0300-5771. 52(5), p. 1579–1591. doi: 10.1093/ije/dyad079. Full text in Research Archive Show summary

  Background Previous Mendelian randomization (MR) studies using population samples (population MR) have provided evidence for beneficial effects of educational attainment on health outcomes in adulthood. However, estimates from these studies may have been susceptible to bias from population stratification, assortative mating and indirect genetic effects due to unadjusted parental genotypes. MR using genetic association estimates derived from within-sibship models (within-sibship MR) can avoid these potential biases because genetic differences between siblings are due to random segregation at meiosis. Methods Applying both population and within-sibship MR, we estimated the effects of genetic liability to educational attainment on body mass index (BMI), cigarette smoking, systolic blood pressure (SBP) and all-cause mortality. MR analyses used individual-level data on 72 932 siblings from UK Biobank and the Norwegian HUNT study, and summary-level data from a within-sibship Genome-wide Association Study including >140 000 individuals. Results Both population and within-sibship MR estimates provided evidence that educational attainment decreased BMI, cigarette smoking and SBP. Genetic variant–outcome associations attenuated in the within-sibship model, but genetic variant–educational attainment associations also attenuated to a similar extent. Thus, within-sibship and population MR estimates were largely consistent. The within-sibship MR estimate of education on mortality was imprecise but consistent with a putative effect. Conclusions These results provide evidence of beneficial individual-level effects of education (or liability to education) on adulthood health, independently of potential demographic and family-level confounders.

• Haftorn, Kristine Løkås; Denault, William Robert Paul; Lee, Yunsung; Page, Christian Magnus; Romanowska, Julia & Lyle, Robert [Show all 12 contributors for this article] (2023). Nucleated red blood cells explain most of the association between DNA methylation and gestational age. Communications Biology. 6. doi: 10.1038/s42003-023-04584-w. Full text in Research Archive Show summary

  Determining if specific cell type(s) are responsible for an association between DNA methylation (DNAm) and a given phenotype is important for understanding the biological mechanisms underlying the association. Our EWAS of gestational age (GA) in 953 newborns from the Norwegian MoBa study identified 13,660 CpGs significantly associated with GA (pBonferroni

• Tesli, Natalia; Jaholkowski, Piotr Pawel; Jaholkowski, Piotr Pawel; Haukvik, Unn Kristin Hansen; Jangmo, Andreas & Haram, Marit [Show all 16 contributors for this article] (2023). Conduct disorder - a comprehensive exploration of comorbidity patterns, genetic and environmental risk factors. Psychiatry Research. ISSN 0165-1781. 331, p. 1–10. doi: 10.1016/j.psychres.2023.115628. Full text in Research Archive
• Tesli, Martin Steen; Nesvåg, Ragnar; Haukvik, Unn Kristin Hansen; Gustavson, Kristin; Tesli, Natalia & Friestad, Christine [Show all 12 contributors for this article] (2023). Common genetic and environmental risk for personality disorders and psychotic-like experiences in young adult twins. Acta Psychiatrica Scandinavica. ISSN 0001-690X. 148(6), p. 561–569. doi: 10.1111/acps.13596. Full text in Research Archive Show summary

  Abstract Introduction Psychotic‐like experiences (PLE) have been associated with the subsequent emergence of psychotic disorders as well as several other domains of psychopathology. In this twin study, we estimated the genetic and environmental correlations between PLE and 10 personality disorders (PD). Methods Diagnoses of 10 PDs according to the Diagnostic and Statistical Manual of Mental Disorders (DSM‐IV) and PLE from the Composite International Diagnostic Interview (CIDI) were retrieved for 2793 young adult twins from the Norwegian Twin Registry. Risk for having a PD and PLEs was modeled using item response theory. Biometric twin models were fitted to estimate the genetic and environmental correlations between PDs and PLEs. Co‐twin control analysis was performed to estimate additional within‐family risk for PLEs when having a PD. Results Phenotypic overlap between PDs and PLEs ranged from 14% to 44% in males and from 11% to 39% in females, with the highest overlap for borderline PD in both sexes. In general, we found higher genetic correlations ( r  = 0.14–0.72) than environmental correlations ( r  = 0.06–0.28) between PDs and PLEs. The highest genetic correlations between PLE and PDs were found for borderline ( r  = 0.72), paranoid ( r  = 0.56), schizotypal ( r  = 0.56) and antisocial PD (r = 0.49). Conclusion We found that the co‐occurrence between PDs and PLE is the best explained by shared genetic determinants, with minor contributions from environmental factors. Interestingly, borderline PD was highly genetically correlated with PLE, warranting molecular genetic studies of this association.

• Choi, Hye Jung; Leblanc, Marissa Erin; Moger, Tron Anders; Valberg, Morten; Aamodt, Geir & Page, Christian Magnus [Show all 8 contributors for this article] (2022). Stroke survival and the impact of geographic proximity to family members: A population-based cohort study. Social Science and Medicine. ISSN 0277-9536. 309. doi: 10.1016/j.socscimed.2022.115252. Full text in Research Archive Show summary

  Introduction Familial support may be important for post-stroke survival. Objective To determine if geographical proximity between stroke survivors and their family members, i.e having a spouse/partner or distance to a nearest first-degree relative (parents, siblings, and offspring), as a proxy for familial support, is related to survivor mortality. Methods This study included all stroke survivors (n=128,227) hospitalised in Norway from 1994 to 2009, who were 30 years or older at the time of the stroke (born before 1965). National registries and censuses were used to calculate the distance to the nearest first-degree relative in the hospitalisation year. Cox proportional hazards models estimated hazard ratios (HRs) of all-cause mortality from 1994 to 2014 (mean 6.4 years follow-up), adjusting for sociodemographic and clinical covariates. Results Living up to 30 km from the nearest first-degree relative was associated with a higher mortality (HR 1.04, 95% CI: 1.03 to 1.06) than those living in the same household or neighbourhood as their nearest first-degree relatives. The association was more pronounced (1.13, 1.08 to 1.19 for ≤30 km; 1.25, 1.16 to 1.35 for >30 km) in survivors hospitalised at age ≤65 years, compared to older survivors. Among familial care predictors, having a spouse/partner was the most prominent predictor of reduced mortality (0.80, 0.78 to 0.82) in stroke survivors. Conclusion Living close to first-degree relatives was weakly associated with better survival in stroke patients while having a spouse/partner exhibited a stronger association. Both associations were larger for survivors hospitalised at age ≤65 years. Our findings thus suggest that the impact of familial support on survival after stroke may differ by familial support condition and patient's age at a stroke hospitalisation.

• Skåra, Karoline Hansen; Åsvold, Bjørn Olav; Camba, Alvaro Hernaez; Fraser, Abigail; Rich-Edwards, Janet Wilson & Farland, Leslie V. [Show all 10 contributors for this article] (2022). Risk of cardiovascular disease in women and men with subfertility: the Trøndelag Health Study. Fertility and Sterility. ISSN 0015-0282. 118(3), p. 537–547. doi: 10.1016/j.fertnstert.2022.05.038. Full text in Research Archive Show summary

  Objective: To investigate the association between subfertility and risk of cardiovascular disease (CVD) outcomes. Design: Prospective study. Setting: Population-based cohort. Patient(s): We studied 31,629 women and 17,630 men participating in the Trøndelag Health Study. Intervention(s): Self-reported subfertility. As men were not directly asked about fertility, male partners of female participants were identified through linkage to the Medical Birth Registry of Norway and assigned the fertility information obtained from their partners. Main outcome measure(s): The primary outcomes were stroke and coronary heart disease in women and men with and without a history of subfertility. The secondary outcomes were myocardial infarction and angina (subgroups of coronary heart disease) and any CVD (stroke or coronary heart disease). Information on CVD was available by linkage to hospital records. We used Cox proportional hazards models adjusted for age at participation in the Trøndelag Health Study (linear + squared), birth year, smoking history, cohabitation, and education. Cardiometabolic factors were assessed in separate models. Result(s): A total of 17% of women and 15% of men reported subfertility. In women, subfertility was modestly associated with an increased risk of stroke (age-adjusted hazard ratio [aaHR], 1.19; 95% confidence interval [CI], 1.02-1.39; adjusted hazard ratio [aHR]; 1.18; 95% CI, 1.01-1.37) and coronary heart disease (aaHR, 1.19; 95% CI, 1.06-1.33; aHR, 1.16; 95% CI, 1.03-1.30) compared with fertile women. In men, we observed a weak positive association for stroke (aaHR, 1.11; 95% CI, 0.91-1.34; aHR, 1.10; 95% CI, 0.91-1.33) and a weak inverse association for coronary heart disease (aaHR, 0.92; 95% CI, 0.81-1.05; aHR, 0.93; 95% CI, 0.81-1.06). Conclusion(s): We observed modestly increased risks of CVD outcomes in women and some weak associations in men, although with no strong statistical evidence on sex differences. We acknowledge that we were only able to include men linked to pregnancies ending at 12 completed gestational weeks or later, potentially resulting in selection bias and misclassification of history of subfertility in analyses of male partners. Despite the large sample size, our results indicate the need for larger studies to obtain precise results in both sexes and determine whether there are true sex differences. Keywords: Subfertility; cardiovascular disease; infertility; the HUNT Study.

• Ystrøm, Eivind; Degerud, Eirik Magnus Meek; Tesli, Martin Steen; Høye, Anne; Reichborn-Kjennerud, Ted & Næss, Øyvind Erik (2022). Alcohol consumption and lower risk of cardiovascular and all-cause mortality: The impact of accounting for familial factors in twins. Psychological Medicine. ISSN 0033-2917. doi: 10.1017/S0033291722000812. Full text in Research Archive Show summary

  Background. A moderate to high alcohol consumption is associated with a lower risk of cardiovascular disease (CVD) mortality in comparison with low consumption. The mechanisms underlying this association are not clear and have been suggested to be caused by residual confounding. The main objective of this study was to separate the familial and individual risk for CVD mortality and all-cause mortality related to alcohol consumption. This will be done by estimating the risk for CVD mortality and all-cause mortality in twin pairs discordant for alcohol consumption.<p> <p>Methods. Alcohol consumption was assessed at two time points using self-report questionnaires in the Norwegian Twin Registry. Data on CVD mortality was obtained from the Norwegian Cause of Death Registry. Exposure–outcome associations for all-cause mortality and mortality due to other causes than CVD were estimated for comparison. <p>Results. Coming from a family with moderate to high alcohol consumption was protective against cardiovascular death (HR = 0.54, 95% CI 0.65–0.83). Moderate and high alcohol consumption levels were associated with a slightly increased risk of CVD mortality at the individual level (HR = 1.33, 95% CI 1.02–1.73). There was no association between alcohol consumption and all-cause mortality both at the familial nor at the individual level. <p>Conclusions. The protective association of moderate to high alcohol consumption with a lower risk of CVD mortality was accounted for by familial factors in this study of twins. Early life genetic and environmental familial factors may mask an absence of health effect of moderate to high alcohol consumption on cardiovascular mortality.

• Howe, Laurence J.; Nivard, Michel G.; Morris, Tim T.; Hansen, Ailin Falkmo; Rasheed, Humaira & Cho, Yoonsu [Show all 105 contributors for this article] (2022). Within-sibship genome-wide association analyses decrease bias in estimates of direct genetic effects. Nature Genetics. ISSN 1061-4036. 54(5), p. 581–592. doi: 10.1038/s41588-022-01062-7. Full text in Research Archive Show summary

  Estimates from genome-wide association studies (GWAS) of unrelated individuals capture effects of inherited variation (direct effects), demography (population stratification, assortative mating) and relatives (indirect genetic effects). Family-based GWAS designs can control for demographic and indirect genetic effects, but large-scale family datasets have been lacking. We combined data from 178,086 siblings from 19 cohorts to generate population (between-family) and within-sibship (within-family) GWAS estimates for 25 phenotypes. Within-sibship GWAS estimates were smaller than population estimates for height, educational attainment, age at first birth, number of children, cognitive ability, depressive symptoms and smoking. Some differences were observed in downstream SNP heritability, genetic correlations and Mendelian randomization analyses. For example, the within-sibship genetic correlation between educational attainment and body mass index attenuated towards zero. In contrast, analyses of most molecular phenotypes (for example, low-density lipoprotein-cholesterol) were generally consistent. We also found within-sibship evidence of polygenic adaptation on taller height. Here, we illustrate the importance of family-based GWAS data for phenotypes influenced by demographic and indirect genetic effects.

• Tesli, Martin Steen; Degerud, Eirik Magnus Meek; Plana-Ripoll, Oleguer; Gustavson, Kristin; Torvik, Fartein Ask & Ystrøm, Eivind [Show all 13 contributors for this article] (2022). Educational attainment and mortality in schizophrenia. Acta Psychiatrica Scandinavica. ISSN 0001-690X. 145(5), p. 481–493. doi: 10.1111/acps.13407. Full text in Research Archive Show summary

  Background Individuals suffering from schizophrenia have a reduced life expectancy with cardiovascular disease (CVD) as a major contributor. Low educational attainment is associated with schizophrenia, as well as with all-cause and CVD mortality. However, it is unknown to what extent low educational attainment can explain the increased mortality in individuals with schizophrenia. Aim Here, we quantify associations between educational attainment and all-cause and CVD mortality in individuals with schizophrenia, and compare them with the corresponding associations in the general population. Method All Norwegian citizens born between January 1, 1925, and December 31, 1959, were followed up from January 1, 1990, to December 31, 2014. The total sample included 1,852,113 individuals, of which 6548 were registered with schizophrenia. We estimated hazard ratios (HR) for all-cause and CVD mortality with Cox models, in addition to life years lost. Educational attainment for index persons and their parents were included in the models. Results In the general population individuals with low educational attainment had higher risk of all-cause (HR: 1.48 [95% CI: 1.47–1.49]) and CVD (HR: 1.59 [95% CI: 1.57–1.61]) mortality. In individuals with schizophrenia these estimates were substantially lower (all-cause: HR: 1.13 [95% CI: 1.05–1.21] and CVD: HR: 1.12 [95% CI: 0.98–1.27]). Low educational attainment accounted for 3.28 (3.21–3.35) life years lost in males and 2.48 (2.42–2.55) years in females in the general population, but was not significantly associated with life years lost in individuals with schizophrenia. Results were similar for parental educational attainment. Conclusions Our results indicate that while individuals with schizophrenia in general have lower educational attainment and higher mortality rates compared with the general population, the association between educational attainment and mortality is smaller in schizophrenia subjects than in the general population.

• Engen, Tone; Owe, Katrine Mari; Horn, Julie; Sulo, Gerhard; Næss, Øyvind Erik & Juliusson, Pétur Benedikt [Show all 8 contributors for this article] (2022). Preconception leisure-time physical activity and family history of stroke and myocardial infarction associate with preterm delivery: findings from a Norwegian cohort. BMC Pregnancy and Childbirth. 22(1). doi: 10.1186/s12884-022-04528-y. Full text in Research Archive Show summary

  Background Preterm birth poses short and long-term health consequences for mothers and offspring including cardiovascular disease sequelae. However, studies evaluating preexisting family history of cardiovascular disease and risk factors, such as physical activity, as they relate prospectively to risk of delivering preterm are lacking. Objectives To evaluate whether preconception past-year weekly leisure-time physical activity or a family history of stroke or of myocardical infarction prior to age 60 years in first degree relatives associated, prospectively, with preterm delivery. Design Cohort study. Baseline data from Cohort Norway (1994–2003) health surveys were linked to the Medical Birth Registry of Norway for identification of all subsequent births (1994–2012). Logistic regression models provided odds ratios (OR) and 95% confidence intervals (CI) for preterm delivery (< 37 weeks gestation); multinomial logistic regression provided OR for early preterm (< 34 weeks) and late preterm (34 through to end of 36 weeks gestation) relative to term deliveries. Results Mean (SD) length of time from baseline health survey participation to delivery was 5.6 (3.5) years. A family history of stroke associated with a 62% greater risk for late preterm deliveries (OR 1.62; CI 1.07–2.47), while a family history of myocardial infarction associated with a 66% greater risk of early preterm deliveries (OR 1.66; CI 1.11–2.49). Sensitivity analyses, removing pregnancies complicated by hypertensive disorders of pregnancy, diabetes mellitus, and stillbirth deliveries, gave similar results. Preconception vigorous physical activity of three or more hours relative to less than 1 h per week associated with increased risk of early preterm delivery (OR 1.52; 95% CI 1.01–2.30), but not late or total preterm deliveries. Light physical activity of three or more hours per week relative to less activity prior to pregnancy was not associated with early, late, or total preterm deliveries. Conclusions Results suggest that family history of cardiovascular disease may help identify women at risk for preterm delivery. Further, research is needed regarding preconception and very early pregnancy vigorous physical activity and associated risks.

• Haftorn, Kristine Løkås; Lee, Yunsung; Denault, William Robert Paul; Page, Christian Magnus; Nustad, Haakon Egdetveit & Lyle, Robert [Show all 17 contributors for this article] (2021). An EPIC predictor of gestational age and its application to newborns conceived by assisted reproductive technologies. Clinical Epigenetics. 13(1). doi: 10.1186/s13148-021-01055-z. Full text in Research Archive Show summary

  Background: Gestational age is a useful proxy for assessing developmental maturity, but correct estimation of gestational age is difcult using clinical measures. DNA methylation at birth has proven to be an accurate predictor of gestational age. Previous predictors of epigenetic gestational age were based on DNA methylation data from the Illumina HumanMethylation 27 K or 450 K array, which have subsequently been replaced by the Illumina MethylationEPIC 850 K array (EPIC). Our aims here were to build an epigenetic gestational age clock specifc for the EPIC array and to evaluate its precision and accuracy using the embryo transfer date of newborns from the largest EPIC-derived dataset to date on assisted reproductive technologies (ART). Methods: We built an epigenetic gestational age clock using Lasso regression trained on 755 randomly selected non-ART newborns from the Norwegian Study of Assisted Reproductive Technologies (START)—a substudy of the Norwegian Mother, Father, and Child Cohort Study (MoBa). For the ART-conceived newborns, the START dataset had detailed information on the embryo transfer date and the specifc ART procedure used for conception. The predicted gestational age was compared to clinically estimated gestational age in 200 non-ART and 838 ART newborns using MM-type robust regression. The performance of the clock was compared to previously published gestational age clocks in an independent replication sample of 148 newborns from the Prediction and Prevention of Preeclampsia and Intrauterine Growth Restrictions (PREDO) study—a prospective pregnancy cohort of Finnish women. Results: Our new epigenetic gestational age clock showed higher precision and accuracy in predicting gestational age than previous gestational age clocks (R2=0.724, median absolute deviation (MAD)=3.14 days). Restricting the analysis to CpGs shared between 450 K and EPIC did not reduce the precision of the clock. Furthermore, validating the clock on ART newborns with known embryo transfer date confrmed that DNA methylation is an accurate predictor of gestational age (R2=0.767, MAD=3.7 days). Conclusions: We present the frst EPIC-based predictor of gestational age and demonstrate its robustness and precision in ART and non-ART newborns. As more datasets are being generated on the EPIC platform, this clock will be valuable in studies using gestational age to assess neonatal development.

• Arge, Lise Andrea; Håberg, Siri Eldevik; Wilcox, Allen J.; Næss, Øyvind Erik; Basso, Olga & Magnus, Maria Christine (2021). The association between miscarriage and fecundability: the Norwegian Mother, Father and Child Cohort Study. Human Reproduction. ISSN 0268-1161. 37(2), p. 322–332. doi: 10.1093/humrep/deab252. Full text in Research Archive Show summary

  Abstract STUDY QUESTION Is fecundability associated with miscarriage history and future miscarriage risk? SUMMARY ANSWER Prior miscarriage was associated with lower fecundability, and participants with a history of subfertility (time-to-pregnancy (TTP) ≥12 months) were at a higher risk of subsequent miscarriage. WHAT IS KNOWN ALREADY Although miscarriage and low fecundability share common risk factors, prior studies have reported both lower and higher fecundability after miscarriage. STUDY DESIGN, SIZE, DURATION In this study, we examined two related associations: one, between miscarriage history and subsequent fecundability and, two, between fecundability and miscarriage risk in the subsequent pregnancy. The study is based on the Norwegian Mother, Father and Child Cohort Study (MoBa). In addition, the outcome of the pregnancy after the MoBa index pregnancy was obtained by linking information from three national health registries: the Medical Birth Registry of Norway, the Norwegian Patient Registry and the general practice database. PARTICIPANTS/MATERIALS, SETTING, METHODS We examined the association between number of prior miscarriages and fecundability in 48 537 naturally conceived, planned pregnancies in participants with at least one prior pregnancy. We estimated fecundability ratios (FRs) and 95% CIs using proportional probability regression. We further estimated the relative risk (RR) of miscarriage in the subsequent pregnancy as a function of TTP in the MoBa index pregnancy for 7889 pregnancies using log-binomial regression. Multivariable analyses adjusted for maternal age, pre-pregnancy maternal BMI, smoking status, cycle regularity, income level and highest completed or ongoing education. MAIN RESULTS AND THE ROLE OF CHANCE Fecundability decreased as the number of prior miscarriages increased. The adjusted FRs among women with one, two and three or more prior miscarriages were 0.83 (95% CI: 0.80–0.85), 0.79 (95% CI: 0.74–0.83) and 0.74 (95% CI: 0.67–0.82), respectively, compared with women with no prior miscarriages. Compared to women with a TTP of &amp;lt;3 months, the adjusted RR of miscarriage in the subsequent pregnancy was 1.16 (0.99–1.35) with TTP of 3–6 months, 1.18 (0.93–1.49) with TTP of 7–11 months and 1.43 (1.13–1.81) with TTP of 12 or more months. LIMITATIONS, REASONS FOR CAUTION Information on TTP and prior miscarriages was obtained retrospectively, and TTP was self-reported. MoBa is a pregnancy cohort, and findings may not be generalizable to all women. We were unable to examine the effect of changing partners between pregnancies, as well as other paternal factors such as seminal parameters. We also did not know what proportion of our participants had changed partners between their prior pregnancies and the index pregnancy. Furthermore, it is likely that many early miscarriages are not recognized. WIDER IMPLICATIONS OF THE FINDINGS The association between miscarriage and fecundability may reflect a contribution of occult pregnancy losses to TTP, as well as shared underlying causes for reduced fecundability and miscarriage. STUDY FUNDING/COMPETING INTEREST(S) The study was funded by the Research Council of Norway through its Medical Student Research Program funding scheme (project number 271555/F20), its Centres of Excellence funding scheme (project number 262700) and through the project ‘Women's fertility – an essential component of health and well-being’ (project number 320656). M.C.M. has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement number 947684). A.J.W. is supported by the Intramural Program of the National Institute of Environmental Health Sciences at the National Institutes of Health, USA. The authors report no competing interests. TRIAL REGISTRATION NUMBER N/A.

• Kjøllesdal, Marte Karoline Råberg; Carslake, David; Smith, G.D.; Shaikh, Fareeha & Næss, Øyvind Erik (2021). The role of family factors in the association between early adulthood BMI and risk of cardiovascular disease. An intergenerational study of BMI in early adulthood and cardiovascular mortality in parents, aunts and uncles. International Journal of Obesity. ISSN 0307-0565. 46, p. 228–234. doi: 10.1038/s41366-021-00987-z. Full text in Research Archive
• Degerud, Eirik Magnus Meek; Høiseth, Gudrun; Mørland, Jørg; Ariansen, Inger Kristine Holtermann; Graff-Iversen, Sidsel & Ystrøm, Eivind [Show all 9 contributors for this article] (2021). Associations of Binge Drinking with the Risks of Ischemic Heart Disease and Stroke: A Study of Pooled Norwegian Health Surveys. American Journal of Epidemiology. ISSN 0002-9262. 190(8), p. 1592–1603. doi: 10.1093/aje/kwab063. Full text in Research Archive Show summary

  Norwegian health survey data (1987 – 2003) were analysed to determine if binge drinking increases the risk of incident major events from ischemic heart disease (IHD) and stroke. Among current drinkers reporting average alcohol intakes between 2 to 60 g/day (n = 44,476), frequent binge drinking (5+ units ≥ once per month) was not associated with a greater risk of IHD (adjusted hazard ratio = 0.91, 95% confidence interval: 0.76, 1.09) nor stroke (adjusted hazard ratio = 0.98, 95% confidence interval: 0.81, 1.19), in comparison with participants who reported that they never or only infrequently (<once per month) had episodes of binge drinking. Participants with an average alcohol intake between 2 – 60 g/day had a lower risk of IHD in comparison with participants with very low intakes (<2 g/day) both among frequent binge drinkers (adjusted hazard ratio = 0.67, 95% confidence interval: 0.56, 0.80) and among never/infrequent binge drinkers (adjusted hazard ratio = 0.75, 95% confidence interval: 0.67, 0.84). The findings suggest that frequent binge drinking does not, independently of the average alcohol intake, increase the risk of incident IHD or stroke events. However, the findings should be interpreted in light of the limitations of the study design.

• Shaikh, Fareeha; Kjøllesdal, Marte Karoline Råberg; Carslake, David; Thoresen, Magne & Næss, Øyvind Erik (2021). Cardiovascular risk factors in extended family members and birthweight in offspring. Journal of Developmental Origins of Health and Disease. ISSN 2040-1744. doi: 10.1017/S2040174421000076. Full text in Research Archive
• Tverdal, Aage; Høiseth, Gudrun; Magnus, Per; Næss, Øyvind; Selmer, Randi & Knudsen, Gun Peggy [Show all 7 contributors for this article] (2021). Alcohol Consumption, HDL-Cholesterol and Incidence of Colon and Rectal Cancer: A Prospective Cohort Study including 250,010 Participants. Alcohol and Alcoholism. ISSN 0735-0414. 56(6), p. 718–725. doi: 10.1093/alcalc/agab007. Full text in Research Archive Show summary

  Aims:Alcohol consumption has been linked to colorectal cancer (CRC) and also to the high-densitylipoprotein cholesterol level (HDL-C). HDL-C has been associated with the incidence of CRC. The aimof this study was to investigate the association between self-reported alcohol consumption, HDL-Cand incidence of CRC, separately for the two sites. Methods:Altogether, 250,010 participants in Norwegian surveys have been followed-up for anaverage of 18 years with respect to a first-time outcome of colon or rectal cancer. During follow-up,3023 and 1439 colon and rectal cancers were registered. Results:For men, the HR per 1 drink per day was 1.05 with 95% confidence interval (0.98–1.12)for colon and 1.08 (1.02–1.15) for rectal cancer. The corresponding figures for women were 1.03(0.97–1.10) and 1.05 (1.00–1.10). There was a positive association between alcohol consumptionand HDL-C. HDL-C was inversely associated with colon cancer in men (0.74 (0.62–0.89) per 1 mmol/l)and positively associated with rectal cancer, although not statistically significant (1.15 (0.92–1.44).A robust regression that assigned weights to each observation and exclusion of weights≤0.1increased the HRs per 1 drink per day and decreased the HR per 1 mmol/l for colon cancer. Theassociations with rectal cancer remained unchanged. Conclusion:Our results support a positive association between alcohol consumption and colonand rectal cancer, most pronounced for rectal cancer. Considering the positive relation betweenalcohol consumption and HDL-C, the inverse association between HDL-C and colon cancer in menremains unsettled.

• Kjøllesdal, Marte Karoline Råberg; Jenum, Anne Karen; Næss, Oyvind & Sletner, Line (2020). The association between birthweight and grandparental type 2 diabetes and cardiovascular disease in a multiethnic population. Journal of Developmental Origins of Health and Disease. ISSN 2040-1744. 11(4), p. 403–409. doi: 10.1017/S2040174419000758. Full text in Research Archive
• Shaikh, Fareeha; Kjøllesdal, Marte Karoline Råberg; Carslake, David; Stoltenberg, Camilla; Smith, George Davey & Næss, Øyvind (2020). Birthweight in offspring and cardiovascular mortality in their parents, aunts and uncles: a family-based cohort study of 1.35 million births. International Journal of Epidemiology. ISSN 0300-5771. 49(1), p. 205–215. doi: 10.1093/ije/dyz156. Full text in Research Archive Show summary

  Background A link between suboptimal fetal growth and higher risk of cardiovascular disease (CVD) is well documented. It has been difficult to assess the contribution of environmental versus genetic factors to the association, as these factors are closely connected in nuclear families. We investigated the association between offspring birthweight and CVD mortality in parents, aunts and uncles, and examined whether these associations are explained by CVD risk factors. Methods We linked Norwegian data from the Medical Birth Registry, the Cause of Death Registry and cardiovascular surveys. A total of 1 353 956 births (1967–2012) were linked to parents and one maternal and one paternal aunt/uncle. Offspring birthweight and CVD mortality association among all relationships was assessed by hazard ratios (HR) from Cox regressions. The influence of CVD risk factors on the associations was examined in a subgroup. Results Offspring birthweight was inversely associated with CVD mortality among parents and aunts/uncles. HR of CVD mortality for one standard deviation (SD) increase in offspring birthweight was 0.72 (0.69–0.75) in mothers and 0.89 (0.86–0.92) in fathers. In aunts/uncles, the HRs were between 0.90 (0.86–0.95) and 0.93 (0.91–0.95). Adjustment for CVD risk factors in a subgroup attenuated all the associations. Conclusions Birthweight was associated with increased risk of CVD in parents and in aunts/uncles. These associations were largely explained by CVD risk factors. Our findings suggest that associations between offspring birthweight and CVD in adult relatives involve both behavioural variables (especially smoking) and shared genetics relating to established CVD risk factors.

• Ariansen, Inger; Degerud, Eirik Magnus Meek; Gjesdal, Knut; Tell, Grethe S. & Næss, Øyvind (2020). Examining the lower range of the association between alcohol intake and risk of incident hospitalization with atrial fibrillation. International journal of cardiology: Heart and Vasculature (IJCHA). 31. doi: 10.1016/j.ijcha.2020.100679. Full text in Research Archive Show summary

  Background Evidence is sparse on the association between alcohol intakes in the lower range and risk of atrial fibrillation (AF). We aimed to investigate self-reported low and moderate alcohol intakes and subsequent risk of incident AF among current drinkers. Methods Norwegian population-based health examination surveys assessing self-reported daily alcohol intake (mean grams per day) were linked to health and population registers. Hazard ratios (HR) (95% confidence interval) for time to incident (first) hospitalization with AF by alcohol intake level were assessed by Cox regression, with adjustment for educational level and cardiovascular risk factors except blood pressure. Results The study population included 234,392 participants (49% men). Incident hospitalization with AF was identified in 5043 (2.2%) persons during a mean follow-up of 9 years. Compared to a very low alcohol intake of <1 unit weekly, a moderate consumption in the range of 1 to <2 units daily increased the risk of incident AF by 18% (HR 1.18 [1.06–1.32]). The average risk of incident AF increased by 9% per daily alcohol unit of 12 g (HR 1.09 [1.03, 1.14]). In sex-stratified analyses significant associations were found in men only. Conclusions We found that less than two alcohol units/day significantly increased the risk of incident AF, however, in men only. Reduction of even a moderate alcohol intake may thus reduce the risk of AF at the population level.

• Kollerud, Ruby Del Risco; Haugnes, Hege Sagstuen; Claussen, Bjørgulf; Thoresen, Magne; Nafstad, Per & Farnham, James [Show all 9 contributors for this article] (2020). A population-based study of testicular cancer risk among children and young adults from Norway and Utah, USA. International Journal of Cancer. ISSN 0020-7136. 147(6). doi: 10.1002/ijc.32949. Full text in Research Archive Show summary

  Similar family-based cancer and genealogy data from Norway and Utah allowed comparisons of the incidence of testicular cancer (TC), and exploration of the role of Scandinavian ancestry and family history of TC in TC risk. Our study utilizes data from the Utah Population Database and Norwegian Population Registers. All males born during 1951–2015 were followed for TC until the age of 29 years. A total of 1,974,287 and 832,836 males were born in Norway and Utah, respectively, of whom 2,686 individuals were diagnosed with TC in Norway and 531 in Utah. The incidence per year of TC in Norway (10.6) was twice that observed in Utah (5.1) for males born in the last period (1980–1984). The incidence rates of TC in Utah did not differ according to the presence or absence of Scandinavian ancestry (p = 0.669). Having a brother diagnosed with TC was a strong risk factor for TC among children born in Norway and Utah, with HR = 9.87 (95% CI 5.68–17.16) and 6.02 (95% CI 4.80–7.55), respectively; with even higher HR observed among the subset of children in Utah with Scandinavian ancestry (HR = 12.30, 95% CI 6.78–22.31). A clear difference in TC incidence among individuals born in Norway and descendants of Scandinavian people born in Utah was observed. These differences in TC rates point to the possibility of environmental influence. Family history of TC is a strong risk factor for developing TC in both populations.

• Degerud, Eirik Magnus Meek; Høiseth, Gudrun; Mørland, Jørg Gustav; Ariansen, Inger; Graff-Iversen, Sidsel & Ystrøm, Eivind [Show all 8 contributors for this article] (2020). Association of coincident self-reported mental health problems and alcohol intake with all-cause and cardiovascular disease mortality: A Norwegian pooled population analysis. PLoS Medicine. ISSN 1549-1277. 17(2), p. 1–21. doi: 10.1371/journal.pmed.1003030. Full text in Research Archive Show summary

  Background The disease burden attributable to mental health problems and to excess or harmful alcohol use is considerable. Despite a strong relationship between these 2 important factors in population health, there are few studies quantifying the mortality risk associated with their co-occurrence in the general population. The aim of this study was therefore to investigate cardiovascular disease (CVD) and all-cause mortality according to self-reported mental health problems and alcohol intake in the general population. Methods and findings We followed 243,372 participants in Norwegian health surveys (1994–2002) through 2014 for all-cause and CVD mortality by data linkage to national registries. The mean (SD) age at the time of participation in the survey was 43.9 (10.6) years, and 47.8% were men. During a mean (SD) follow-up period of 16.7 (3.2) years, 6,587 participants died from CVD, and 21,376 died from all causes. Cox models estimated hazard ratios (HRs) with 95% CIs according to a mental health index (low, 1.00–1.50; high, 2.01–4.00; low score is favourable) based on the General Health Questionnaire and the Hopkins Symptom Checklist, and according to self-reported alcohol intake (low, <2; light, 2–11.99; moderate, 12–23.99; high, ≥24 grams/day). HRs were adjusted for age, sex, educational level, marital status, and CVD risk factors. Compared to a reference group with low mental health index score and low alcohol intake, HRs (95% CIs) for all-cause mortality were 0.93 (0.89, 0.97; p = 0.001), 1.00 (0.92, 1.09; p = 0.926), and 1.14 (0.96, 1.35; p = 0.119) for low index score combined with light, moderate, and high alcohol intake, respectively. HRs (95% CIs) were 1.22 (1.14, 1.31; p < 0.001), 1.24 (1.15, 1.33; p < 0.001), 1.43 (1.23, 1.66; p < 0.001), and 2.29 (1.87, 2.80; p < 0.001) for high index score combined with low, light, moderate, and high alcohol intake, respectively. For CVD mortality, HRs (95% CIs) were 0.93 (0.86, 1.00; p = 0.058), 0.90 (0.76, 1.07; p = 0.225), and 0.95 (0.67, 1.33; p = 0.760) for a low index score combined with light, moderate, and high alcohol intake, respectively, and 1.11 (0.98, 1.25; p = 0.102), 0.97 (0.83, 1.13; p = 0.689), 1.01 (0.71, 1.44; p = 0.956), and 1.78 (1.14, 2.78; p = 0.011) for high index score combined with low, light, moderate, and high alcohol intake, respectively. HRs for the combination of a high index score and high alcohol intake (HRs: 2.29 for all-cause and 1.78 for CVD mortality) were 64% (95% CI 53%, 74%; p < 0.001) and 69% (95% CI 42%, 97%; p < 0.001) higher than expected for all-cause mortality and CVD mortality, respectively, under the assumption of a multiplicative interaction structure. A limitation of our study is that the findings were based on average reported intake of alcohol without accounting for the drinking pattern. Conclusions In the general population, the mortality rates associated with more mental health problems and a high alcohol intake were increased when the risk factors occurred together.

• Kollerud, Ruby Del Risco; Cannon-Albright, LA; Haugnes, Hege Sagstuen; Ruud, Ellen; Thoresen, Magne & Nafstad, Per [Show all 9 contributors for this article] (2020). Childhood central nervous system tumors and leukemia: Incidence and familial risk. A comparative population-based study in Utah and Norway. Pediatric Blood & Cancer. ISSN 1545-5009. Aug;67(8):e28408. doi: 10.1002/pbc.28408. Full text in Research Archive Show summary

  Background In this study, we aimed to evaluate incidence rates and family risk of the most common childhood cancers, tumors in the central nervous system (CNS), and leukemia among individuals from Norway and individuals with Scandinavian ancestry living in Utah. Methods We used the Utah Population Database and the Norwegian National Population Register linked to Cancer registries to identify cancers in children born between 1966 and 2015 and their first‐degree relatives. We calculated incidence rates and hazards ratios. Results The overall incidence of CNS tumors increased with consecutive birth cohorts similarly in Utah and Norway (both P < 0.001). Incidence rates of leukemia were more stable and similar in both Utah and in Norway with 4.6/100 000 person‐years among children (<15 years) born in the last cohort. A family history of CNS tumors was significantly associated with risk of childhood CNS tumors in Utah HR = 3.05 (95% CI 1.80‐5.16) and Norway HR = 2.87 (95% CI 2.20‐3.74). In Norway, children with a first‐degree relative diagnosed with leukemia had high risk of leukemia (HR = 2.39, 95% CI 1.61‐3.55). Conclusion Despite geographical distance and assumed large lifestyle differences, two genetically linked pediatric populations show similar incidences of CNS tumors and leukemia in the period 1966–2015. CNS tumors and leukemia aggregated in families in both countries.

• Heiberg, Ina Heidi; Nesvåg, Ragnar; Balteskard, Lise; Bramness, Jørgen Gustav; Hultman, Christina M. & Næss, Øyvind [Show all 10 contributors for this article] (2020). Diagnostic tests and treatment procedures performed prior to cardiovascular death in individuals with severe mental illness. Acta Psychiatrica Scandinavica. ISSN 0001-690X. 141(5), p. 439–451. doi: 10.1111/acps.13157. Full text in Research Archive Show summary

  <p><i>Objective - </i>To examine whether severe mental illnesses (i.e., schizophrenia or bipolar disorder) affected diagnostic testing and treatment for cardiovascular diseases in primary and specialized health care. <p><i>Methods - </i>We performed a nationwide study of 72 385 individuals who died from cardiovascular disease, of whom 1487 had been diagnosed with severe mental illnesses. Log‐binomial regression analysis was applied to study the impact of severe mental illnesses on the uptake of diagnostic tests (e.g., 24‐h blood pressure, glucose/HbA1c measurements, electrocardiography, echocardiography, coronary angiography, and ultrasound of peripheral vessels) and invasive cardiovascular treatments (i.e., revascularization, arrhythmia treatment, and vascular surgery). <p><i>Results - </i>Patients with and without severe mental illnesses had similar prevalences of cardiovascular diagnostic tests performed in primary care, but patients with schizophrenia had lower prevalences of specialized cardiovascular examinations (prevalence ratio (PR) 0.78; 95% CI 0.73–0.85). Subjects with severe mental illnesses had lower prevalences of invasive cardiovascular treatments (schizophrenia, PR 0.58; 95% CI 0.49–0.70, bipolar disorder, PR 0.78; 95% CI 0.66–0.92). The prevalence of invasive cardiovascular treatments was similar in patients with and without severe mental illnesses when cardiovascular disease was diagnosed before death. <p><i>Conclusion - </i>Better access to specialized cardiovascular examinations is important to ensure equal cardiovascular treatments among individuals with severe mental illnesses.

• Ariansen, Inger; Strand, Bjørn Heine; Kjøllesdal, Marte Karoline Råberg; Steingrímsdóttir, Ólöf Anna; Mortensen, Laust Hvas & Stigum, Hein [Show all 8 contributors for this article] (2019). The educational gradient in premature cardiovascular mortality: Examining mediation by risk factors in cohorts born in the 1930s, 1940s and 1950s. European Journal of Preventive Cardiology (EJPC). ISSN 2047-4873. 26(10), p. 1096–1103. doi: 10.1177/2047487319826274. Full text in Research Archive Show summary

  <i>Aims</i>: Educational inequality in cardiovascular disease and in modifiable risk factors changes over time and between birth cohorts. We aimed to assess how cardiovascular disease risk factors mediate educational differences in premature cardiovascular disease mortality and how this varies over birth cohorts and sex.<p> <p><i>Methods</i>: We followed 360,008 40–45-year-olds born in the 1930s, 1940s or 1950s from Norwegian health examination surveys (1974–1997) for premature cardiovascular disease mortality. Cox proportional hazard and Aalen’s additive survival analyses provided hazard ratios and rate differences of excess deaths in participants with basic versus tertiary education.<p> <p><i>Results</i>: Relative educational differences in premature cardiovascular disease mortality were stable, whereas absolute differences narrowed from the 1930s to the 1950s cohorts; rate differences per 100 000 person years declined from 170 (95% confidence interval 117, 224) to 49 (36, 61) in men and from 60 (34, 85) to 23 (16, 29) in women. Cardiovascular disease risk factors attenuated rate differences by 69% in both cohorts in men, and in women by 102% in 1930s and 61% in 1950s cohorts. Smoking had the single strongest influence on the educational differences for men in all three cohorts, and for women in the two most recent cohorts.<p> <p><i>Conclusion</i>: Smoking appeared to be the driving force behind educational differences in premature cardiovascular disease mortality in the 1930s to 1950s birth cohorts for men and in the two recent birth cohorts for women. This suggests that strategies for smoking prevention and cessation might have the strongest impact for reducing educational inequality in premature cardiovascular disease mortality.<p>

• Fossum, Stine; Næss, Øyvind; Halvorsen, Sigrun; Tell, Grethe S. & Vikanes, Åse (2019). Long-term cardiovascular morbidity following hyperemesis gravidarum: A Norwegian nationwide cohort study. PLOS ONE. 14:e0218051(6), p. 1–12. doi: 10.1371/journal.pone.0218051. Full text in Research Archive Show summary

  Objective: To investigate whether exposure to hyperemesis gravidarum (hyperemesis) is associated with subsequent maternal cardiovascular morbidity. Design: Nationwide cohort study. Setting: Medical Birth Registry of Norway (1967–2002) linked to the nationwide Cardiovascular Disease in Norway project 1994–2009 (CVDNOR) and the Cause of Death Registry. Population: Women in Norway with singleton births from 1967 to 2002, with and without hyperemesis, were followed up with respect to cardiovascular outcomes from 1994 to 2009. Methods: Cox proportional hazards regression model was applied to estimate hazard ratios (HRs) with 95% confidence interval (CI). Main outcome measures The first hospitalisation due to nonfatal stroke, myocardial infarction or angina pectoris, or cardiovascular death. Results: Among 989 473 women with singleton births, 13 212 (1.3%) suffered from hyperemesis. During follow-up, a total of 43 482 (4.4%) women experienced a cardiovascular event. No association was found between hyperemesis and the risk of a fatal or nonfatal cardiovascular event (adjusted HR 1.08; 95% CI 0.99–1.18). Women with hyperemesis had higher risk of hospitalisation due to angina pectoris (adjusted HR 1.28; 95% CI 1.15–1.44). The risk of cardiovascular death was lower among hyperemetic women in age-adjusted analysis (HR 0.73; 95% CI 0.59–0.91), but the association was no longer significant when adjusting for possible confounders. Conclusion: Women with a history of hyperemesis did not have increased risk of a cardiovascular event (nonfatal myocardial infarction or stroke, angina pectoris or cardiovascular death) compared to women without.

• Kjøllesdal, Marte Karoline Råberg; Ariansen, Inger & Næss, Øyvind (2019). Early adulthood weight, subsequent midlife weight change and risk of cardiovascular disease mortality: an analysis of Norwegian cardiovascular surveys. International Journal of Obesity. ISSN 0307-0565. doi: 10.1038/s41366-019-0467-0. Full text in Research Archive
• Kjøllesdal, Marte Karoline Råberg; Degerud, Eirik Magnus Meek & Næss, Øyvind (2019). The association between obesity and cardiovascular disease mortality in different strata of socioeconomic position: Evidence from pooled Norwegian health surveys. European Journal of Public Health. ISSN 1101-1262. 29(6), p. 1160–1166. doi: 10.1093/eurpub/ckz141. Full text in Research Archive Show summary

  BACKGROUND: Socioeconomic position (SEP) is related to both obesity and cardiovascular disease (CVD). There is little evidence on whether SEP modifies the relation between obesity and CVD. The aim of the study was to investigate whether the association between obesity and CVD mortality is stronger among people with disadvantaged than among people with advantaged life course SEP. METHODS: Data from Norwegian population-based cardiovascular health surveys (1985-2003), including body mass index and CVD risk factors (cholesterol, blood pressure, smoking, current treatment for hypertension) were linked to socioeconomic indicators from register and census data (1960-90), and to the Cause of Death Registry (up until 2014). The total number of participants was 398 297. RESULTS: In comparison with normal weight, the age-adjusted hazard ratios and 95% confidence intervals of CVD mortality among obese participants were 2.39 (2.07-2.75) and 2.08 (1.70-2.53) among men and women with high SEP, respectively and 1.88 (1.60-2.21) and 1.75 (1.43-2.14) among men and women with low SEP. Adjustment for CVD risk factors attenuated the results in a similar manner in all SEP groups, and among both women and men. CONCLUSION: Obesity was consistently associated with a higher risk of CVD mortality, with only minor variation according to SEP. This means that preventing or treating obesity is, for the purpose of reducing CVD risk, equally important for an individual with high or low SEP.

• Kollerud, Ruby Del Risco; Ruud, Ellen; Haugnes, Hege Sagstuen; Cannon-Albright, Lisa A.; Thoresen, Magne & Nafstad, Per [Show all 10 contributors for this article] (2019). Family history of cancer and risk of paediatric and young adult’s testicular cancer: A Norwegian cohort study. British Journal of Cancer. ISSN 0007-0920. 120, p. 1007–1014. doi: 10.1038/s41416-019-0445-2. Full text in Research Archive Show summary

  <i>Background</i> - The aim of this study was to examine the association of a family history of cancer with the risk of testicular cancer in young adults.<p><p> <i>Methods</i> - This is a prospective cohort study including 1,974,287 males born 1951–2015, of whom 2686 were diagnosed with TC before the age of 30.<p><p> <i>Results</i> - A history of TC in male relatives was significantly associated with a diagnosis of TC among children and young adults, including brothers (6.3-fold), sons (4.7-fold), fathers (4.4-fold), paternal uncles (2.0-fold) and maternal uncles (1.9-fold). Individuals with a father diagnosed with a carcinoma or sarcoma showed an elevated risk (1.1-fold and 1.8-fold, respectively). A family history of mesothelioma was positively associated with a risk of TC [(father (2.8-fold), mother (4.6-fold) and maternal uncles and aunt (4.4-fold)]. Elevated risks were also observed when siblings were diagnosed with malignant melanoma (1.4-fold). The risk of TC was also increased when fathers (11.1-fold), paternal (4.9-fold) and maternal uncles and aunts (4.6-fold) were diagnosed with malignant neuroepithelial-tumours.<p><p> <i>Conclusion</i> - We found an increased risk of TC among children and young adults with a family history of TC, carcinoma, mesothelioma, sarcoma, malignant melanoma and malignant neuroepithelial tumours. Hereditary cancer syndromes might underlie some of the associations reported in this study.

• Heiberg, Ina Heidi; Jacobsen, Bjarne K.; Balteskard, Lise; Bramness, Jørgen Gustav; Næss, Øyvind & Ystrøm, Eivind [Show all 10 contributors for this article] (2019). Undiagnosed cardiovascular disease prior to cardiovascular death in individuals with severe mental illness. Acta Psychiatrica Scandinavica. ISSN 0001-690X. 139(6), p. 558–571. doi: 10.1111/acps.13017. Full text in Research Archive Show summary

  <p><i>Objective - </i>To examine whether individuals with schizophrenia (SCZ) or bipolar disorder (BD) had equal likelihood of not being diagnosed with cardiovascular disease (CVD) prior to cardiovascular death, compared to individuals without SCZ or BD. <p><i>Methods - </i>Multivariate logistic regression analysis including nationwide data of 72 451 cardiovascular deaths in the years 2011–2016. Of these, 814 had a SCZ diagnosis and 673 a BD diagnosis in primary or specialist health care. <p><i>Results - </i>Individuals with SCZ were 66% more likely (OR: 1.66; 95% CI: 1.39–1.98), women with BD were 38% more likely (adjusted OR: 1.38; 95% CI: 1.04–1.82), and men with BD were equally likely (OR: 0.88, 95% CI: 0.63–1.24) not to be diagnosed with CVD prior to cardiovascular death, compared to individuals without SMI. Almost all (98%) individuals with SMI and undiagnosed CVD had visited primary or specialized somatic health care prior to death, compared to 88% among the other individuals who died of CVD. <p><i>Conclusion - </i>Individuals with SCZ and women with BD are more likely to die due to undiagnosed CVD, despite increased risk of CVD and many contacts with primary and specialized somatic care. Strengthened efforts to prevent, recognize, and treat CVD in individuals with SMI from young age are needed.

• Gebremariam, Mekdes Kebede; Arah, Onyebuchi A.; Lien, Nanna; Næss, Øyvind; Ariansen, Inger Kristine Holtermann & Kjøllesdal, Marte Karoline Råberg (2018). Change in BMI Distribution over a 24-Year Period and Associated Socioeconomic Gradients: A Quantile Regression Analysis. Obesity. ISSN 1930-7381. 26(4), p. 769–775. doi: 10.1002/oby.22133. Full text in Research Archive Show summary

  ObjectiveThis study assessed the change in body mass index (BMI) distribution among 18- or 19-year-olds over 24 years. It also investigated parallel changes in the distribution of birth weight and in the association between birth weight and later risk of overweight and/or obesity. Parental educational variations in the trends and associations were explored. MethodsThe study used data on 606,832 male military conscripts enlisted between 1985 and 2008. Quantile regression was used to assess the temporal change in BMI and birth weight distribution. The association between birth weight and overweight and/or obesity at age 18 or 19 years was quantified by using logistic regression. ResultsIncreases in BMI over time were found namely in the 90th, 95th, 97th, and 99th percentiles. Socioeconomic differences in this increase were documented in the 75th to 97th percentiles. The distribution of birth weight and the association between birth weight and the risk of overweight and/or obesity at age 18 or 19 years remained stable over time. ConclusionsThe difference in the increase in BMI between low and high percentiles indicates the limited role of mean BMI in reflecting population changes. The results suggest a need to focus on those with low socioeconomic position in the upper ends of the BMI distribution to combat increasing disparities in obesity-related outcomes.

• Ebbing, Marta; Reneflot, Anne; Hjellvik, Vidar; Næss, Øyvind & Meltzer, Helle Margrete (2018). Kunnskapskilder for folkehelse. In Grøholt, Else Karin; Bøhler, Linn & Hånes, Hanna (Ed.), Folkehelserapporten - Helsetilstanden i Norge. Folkehelseinstituttet. Full text in Research Archive
• Shaikh, Fareeha; Kjøllesdal, Marte Karoline Råberg & Næss, Øyvind (2018). Offspring birth weight and cardiovascular mortality among parents: the role of cardiovascular risk factors. Journal of Developmental Origins of Health and Disease. ISSN 2040-1744. 9(3), p. 351–357. doi: 10.1017/S2040174418000065. Full text in Research Archive Show summary

  An inverse association between offspring birth weight (BW) and higher risk of parental cardiovascular disease (CVD) mortality and morbidity has been reported. Shared environmental, genetic and intrauterine factors may be responsible for explaining these associations. We studied the role of parental CVD risk factors in the association between offspring BW and CVD mortality among mothers and fathers. All births registered in Medical Birth Registry Norway (1967–2012) were linked to three health surveys, National Educational Registry and Cause of Death Registry. Number of births with information of parental CVD risk factors available for the analyses was 1,006,557 (520,670 for mothers and 485,887 for fathers). Cox proportional hazards regression models were used, following CVD deaths in parents from 1974 to 2012. An inverse association between offspring BW and CVD mortality was observed among both parents: hazard ratio 1.60 (1.44–1.75) for mothers and 1.16 (1.10–1.23) for fathers. Among mothers, adjustment for smoking, triglycerides and diabetes reduced the risk to 1.36 (1.25–1.52), 1.57 (1.43–1.73) and 1.58 (1.43–1.79), respectively. Adjustment for diastolic blood pressure (DBP) and systolic blood pressure (SBP) both reduced the risk to 1.53 (1.37–1.66). Among fathers, adjustments for smoking, DBP, SBP reduced the risk to 1.08 (1.02–1.15), 1.13 (1.06–1.19) and 1.14 (1.08–1.22), respectively. Triglycerides and diabetes both reduced the risk to 1.15 (1.09–1.12). Our results indicate that shared environmental factors might be important in the association. A stronger association in mothers suggest that intrauterine factors also are at play.

• Graff-Iversen, Sidsel; Ariansen, Inger Kristine Holtermann; Næss, Øyvind; Selmer, Randi & Strand, Bjørn Heine (2018). Educational inequalities in midlife risk factors for non-communicable diseases in two Norwegian counties 1974–2002. Scandinavian Journal of Public Health. ISSN 1403-4948. doi: 10.1177/1403494818789325. Full text in Research Archive
• Kjøllesdal, Marte Karoline Råberg; Smith, George Davey; Ariansen, Inger Kristine Holtermann; Kinge, Jonas Minet; Degerud, Eirik & Næss, Øyvind (2018). The association between BMI and mortality using early adulthood BMI as an instrumental variable for midlife BMI. Scientific Reports. 8(1). doi: 10.1038/s41598-018-29089-z. Full text in Research Archive Show summary

  The article aims to describe the association between midlife body mass index (BMI) and cardiovascular disease (CVD)- and all-cause mortality, and to use early adulthood BMI as an instrumental variable for midlife BMI, in order to obtain an estimate less distorted by midlife confounders and reverse causality. Data from Norwegian health surveys (1974–2003) (midlife BMI, smoking, blood pressure, total cholesterol, heart rate), Military Conscription Records, National Tuberculosis Screenings (early adulthood BMI), National Educational Registry and Cause of Death Registry were linked. Participants with data on BMI in early adulthood and midlife were included (n = 148.886). Hazard Ratio (HR) for CVD mortality was higher in men with midlife obesity relative to normal weight (HR = 1.46(95% CI 1.25, 1.70). For all-cause mortality, HR was higher in those with obesity or underweight in midlife relative to normal weight (Men:HR = 1.19(95% CI 1.09, 1.29), HR = 2.49(95% CI 1.81, 3.43) Women:HR = 1.33(95% CI 1.13, 1.56), HR = 1.61(95% CI 1.22, 2.13)). In instrumental variable analyses, increased BMI became more strongly associated with CVD and all-cause mortality, and the increased risk of all-cause mortality among the underweight attenuated.

• Kollerud, Ruby Del Risco; Blaasaas, Karl Gerhard; Claussen, Bjørgulf; Nafstad, Per; Cannon-Albright, Lisa A. & Ruud, Ellen [Show all 8 contributors for this article] (2018). Family history of cancer and the risk of childhood solid tumours: A Norwegian nationwide register-based cohort study. British Journal of Cancer. ISSN 0007-0920. 118(6), p. 905–912. doi: 10.1038/bjc.2017.493. Full text in Research Archive
• Heiberg, Ina Heidi; Jacobsen, Bjarne K.; Nesvåg, Ragnar; Bramness, Jørgen Gustav; Reichborn-Kjennerud, Ted & Næss, Øyvind [Show all 9 contributors for this article] (2018). Total and cause-specific standardized mortality ratios in patients with schizophrenia and/or substance use disorder. PLOS ONE. 13(8). doi: 10.1371/journal.pone.0202028. Full text in Research Archive Show summary

  Individuals with schizophrenia or substance use disorder have a substantially increased mortality compared to the general population. Despite a high and probably increasing prevalence of comorbid substance use disorder in people with schizophrenia, the mortality in the comorbid group has been less studied and with contrasting results. We performed a nationwide open cohort study from 2009 to 2015, including all Norwegians aged 20–79 with schizophrenia and/or substance use disorder registered in any specialized health care setting in Norway, a total of 125,744 individuals. There were 12,318 deaths in the cohort, and total, sex-, age- and cause-specific standardized mortality ratios (SMRs) were calculated, comparing the number of deaths in patients with schizophrenia, schizophrenia only, substance use disorder only or a co-occurring diagnosis of schizophrenia and substance use disorder to the number expected if the patients had the age-, sex- and calendar-year specific death rates of the general population. The SMRs were 4.9 (95% CI 4.7–5.1) for all schizophrenia patients, 4.4 (95% CI 4.2–4.6) in patients with schizophrenia without substance use disorder, 6.6 (95% CI 6.5–6.8) in patients with substance use disorder only, and 7.4 (95% CI 7.0–8.2) in patients with both schizophrenia and substance use disorder. The SMRs were elevated in both genders, in all age groups and for all considered causes of death, and most so in the youngest. Approximately 27% of the excess mortality in all patients with schizophrenia was due to the raised mortality in the subgroup with comorbid SUD. The increased mortality in patients with schizophrenia and/or substance use disorder corresponded to more than 10,000 premature deaths, which constituted 84% of all deaths in the cohort. The persistent mortality gap highlights the importance of securing systematic screening and proper access to somatic health care, and a more effective prevention of premature death from external causes in this group.

• Degerud, Eirik; Ariansen, Inger Kristine Holtermann; Ystrøm, Eivind; Graff-Iversen, Sidsel; Høiseth, Gudrun & Mørland, Jørg [Show all 8 contributors for this article] (2018). Life course socioeconomic position, alcohol drinking patterns in midlife, and cardiovascular mortality: Analysis of Norwegian population-based health surveys. PLoS Medicine. ISSN 1549-1277. 15(1). doi: 10.1371/journal.pmed.1002476. Full text in Research Archive Show summary

  Background: Socioeconomically disadvantaged groups tend to experience more harm from the same level of exposure to alcohol as advantaged groups. Alcohol has multiple biological effects on the cardiovascular system, both potentially harmful and protective. We investigated whether the diverging relationships between alcohol drinking patterns and cardiovascular disease (CVD) mortality differed by life course socioeconomic position (SEP). Methods and findings: From 3 cohorts (the Counties Studies, the Cohort of Norway, and the Age 40 Program, 1987–2003) containing data from population-based cardiovascular health surveys in Norway, we included participants with self-reported information on alcohol consumption frequency (n = 207,394) and binge drinking episodes (≥5 units per occasion, n = 32,616). We also used data from national registries obtained by linkage. Hazard ratio (HR) with 95% confidence intervals (CIs) for CVD mortality was estimated using Cox models, including alcohol, life course SEP, age, gender, smoking, physical activity, body mass index (BMI), systolic blood pressure, heart rate, triglycerides, diabetes, history of CVD, and family history of coronary heart disease (CHD). Analyses were performed in the overall sample and stratified by high, middle, and low strata of life course SEP. A total of 8,435 CVD deaths occurred during the mean 17 years of follow-up. Compared to infrequent consumption (<once/month), moderately frequent consumption (2–3 times per week) was associated with a lower risk of CVD mortality (HR = 0.78, 95% CI 0.72, 0.84) overall. HRs for the high, middle, and low strata of SEP were 0.66 (95% CI 0.58, 0.76), 0.87 (95% CI 0.78, 0.97), and 0.79 (95% CI 0.64, 0.98), respectively, compared with infrequent users in each stratum. HRs for effect modification were 1.30 (95% CI 1.10, 1.54, p = 0.002; middle versus high), 1.23 (95% CI 0.96, 1.58, p = 0.10; low versus high), and 0.96 (95% CI 0.76, 1.21, p = 0.73; low versus middle). In the group with data on binge drinking, 2,284 deaths (15 years) from CVDs occurred. In comparison to consumers who did not binge during the past year, HRs among frequent bingers (≥1 time per week) were 1.58 (95% CI 1.31, 1.91) overall, and 1.22 (95% CI 0.84, 1.76), 1.71 (95% CI 1.31, 2.23), and 1.85 (95% CI 1.16, 2.94) in the strata, respectively. HRs for effect modification were 1.36 (95% CI 0.87, 2.13, p = 0.18; middle versus high), 1.63 (95% CI 0.92, 2.91, p = 0.10; low versus high), and 1.32 (95% CI 0.79, 2.20, p = 0.29; low versus middle). A limitation of this study was the use of a single measurement to reflect lifetime alcohol consumption. Conclusions: Moderately frequent consumers had a lower risk of CVD mortality compared with infrequent consumers, and we observed that this association was more pronounced among participants with higher SEP throughout their life course. Frequent binge drinking was associated with a higher risk of CVD mortality, but it was more uncertain whether the risk differed by life course SEP. It is unclear if these findings reflect differential confounding of alcohol consumption with health-protective or damaging exposures, or differing effects of alcohol on health across socioeconomic groups.

• Fossum, Stine; Halvorsen, Sigrun; Vikanes, Åse Vigdis; Roseboom, Tessa J.; Ariansen, Inger Kristine Holtermann & Næss, Øyvind (2018). Cardiovascular risk profile at the age of 40?45 in women with previous hyperemesis gravidarum or hypertensive disorders in pregnancy: A population-based study. Pregnancy Hypertension. ISSN 2210-7789. 12, p. 129–135. doi: 10.1016/j.preghy.2018.04.013. Full text in Research Archive
• Næss, Øyvind; Mortensen, Laust H.; Vikanes, Åse Vigdis & Smith, George Davey (2017). Offspring sex and parental health and mortality. Scientific Reports. 7. doi: 10.1038/s41598-017-05161-y. Full text in Research Archive Show summary

  Increased mortality has been observed in mothers and fathers with male offspring but little is known regarding specific diseases. In a register linkage we linked women born 1925–1954 having survived to age 50 (n = 661,031) to offspring and fathers (n = 691,124). Three approaches were used: 1) number of total boy and girl offspring, 2) sex of the first and second offspring and 3) proportion of boys to total number of offspring. A sub-cohort (n = 50,736 mothers, n = 44,794 fathers) from survey data was analysed for risk factors. Mothers had increased risk of total and cardiovascular mortality that was consistent across approaches: cardiovascular mortality of 1.07 (95% CI: 1.03–1.11) per boy (approach 2), 1.04 (1.01–1.07) if the first offspring was a boy, and 1.06 (1.01–1.10) if the first two offspring were boys (approach 3). We found that sex of offspring was not associated with total or cardiovascular mortality in fathers. For other diseases or risk factors no robust associations were seen in mothers or fathers. Increased cardiovascular risk in mothers having male offspring suggests a maternal disease specific mechanism. The lack of consistent associations on measured risk factors could suggest other biological pathways than those studied play a role in generating this additional cardiovascular risk.

• Kollerud, Ruby Del Risco; Blaasaas, Karl Gerhard; Claussen, Bjørgulf; Oftedal, Bente Margaret & Næss, Øyvind (2017). The risk of cancer in the offspring and parental length of life. Cancer Epidemiology. ISSN 1877-7821. 48, p. 8–15. doi: 10.1016/j.canep.2017.02.012. Full text in Research Archive
• Kjøllesdal, Marte Karoline Råberg; Ariansen, Inger Kristine; Mortensen, Laust H & Næss, Øyvind (2017). The importance of early life family factors in the association between cardiovascular risk factors and early cardiovascular mortality. Open heart. 4(2). doi: 10.1136/openhrt-2017-000608. Full text in Research Archive Show summary

  Objective: To explore the importance of early life factors shared by siblings, such as parental socioeconomic position, parental practices, housing and neighbourhood, for the association between cardiovascular disease (CVD) risk factors and mortality from CVD, ischaemic heart disease (IHD) and cerebrovascular disease. Methods: Norwegian health surveys (1974–2003) were linked with data from the Norwegian Family Based Life Course Study and the Cause of Death Registry. Participants with at least one full sibling among survey participants (n=2 71 643) were included. Data on CVD risk factors, body mass index (BMI), height, systolic blood pressure (SBP) and total cholesterol (TC) were stratified into ‘low’, ‘medium’ and ‘high’ risk, and smoking to ‘daily smoking’ and ‘not daily smoking’. Results: Mean age of participants was 41 years, mean follow-up time was 19 years and during follow-up 2512 died from CVD. For each category of increased risk factor level, the per step HR of CVD mortality was increased by 1.91 (95% CI 1.78 to 2.05) for SBP, 1.67 (1.58 to 1.76) for TC, 1.44 (1.36 to 1.53) for BMI, 1.26 (1.18 to 1.35) for height and 2.89 (2.66 to 3.14) for smoking. In analyses where each sibship (groups of full siblings) had a group-specific baseline hazard, these associations were attenuated to 1.74, 1.51, 1.29, 1.18 and 2.63, respectively. The associations between risk factors and IHD mortality followed the same pattern. Conclusion: Early life family factors explained a small part of the association between risk factors and mortality from CVD and IHD in a relatively young sample.

• Ariansen, Inger Kristine; Mortensen, Laust Hvas; Graff-Iversen, Sidsel; Stigum, Hein; Kjøllesdal, Marte Karoline Råberg & Næss, Øyvind (2017). The educational gradient in cardiovascular risk factors: impact of shared family factors in 228,346 Norwegian siblings. BMC Public Health. 17(1). doi: 10.1186/s12889-017-4123-0. Full text in Research Archive Show summary

  <p><b>Background:</b> Various indicators of childhood socioeconomic position have been related to cardiovascular disease (CVD) risk in adulthood. We investigated the impact of shared family factors on the educational gradient in midlife CVD risk factors by assessing within sibling similarities in the gradient using a discordant sibling design.</p> <p><b>Methods:</b> Norwegian health survey data (1980–2003) was linked to educational and generational data. Participants with a full sibling in the health surveys (228,346 individuals in 98,046 sibships) were included. Associations between attained educational level (7–9 years, 10–11 years, 12 years, 13–16 years, or >16 years) and CVD risk factor levels in the study population was compared with the corresponding associations within siblings.</p> <p><b>Results:</b> Educational gradients in risk factors were attenuated when factors shared by siblings was taken into account: A one category lower educational level was associated with 0.7 (95% confidence interval 0.6 to 0.8) mm Hg higher systolic blood pressure (27% attenuation), 0.4 (0.4 to 0.5) mmHg higher diastolic blood pressure (30%), 1.0 (1.0 to 1.1) more beats per minute higher heart rate (21%), 0.07 (0.06 to 0.07) mmol/l higher serum total cholesterol (32%), 0.2 (0.2 to 0.2) higher smoking level (5 categories) (30%), 0.15 (0.13 to 0.17) kg/m2 higher BMI (43%), and 0.2 (0.2 to 0.2) cm lower height (52%). Attenuation increased with shorter age-difference between siblings.</p> <p><b>Conclusion:</b> About one third of the educational gradients in modifiable CVD risk factors may be explained by factors that siblings share. This implies that childhood environment is important for the prevention of CVD

• Fossum, Stine; Vikanes, Åse Vigdis; Næss, Øyvind; Vos, Linda; Grotmol, Tom & Halvorsen, Sigrun (2017). Hyperemesis gravidarum and long-term mortality: a population-based cohort study. BJOG: An International Journal of Obstetrics and Gynaecology. ISSN 1470-0328. 124(7), p. 1080–1087. doi: 10.1111/1471-0528.14454. Full text in Research Archive Show summary

  Objective To investigate whether exposure to hyperemesis gravidarum (HG) is associated with increased maternal long-term mortality. Results Of 999 161 women with singleton births, 13 397 (1.3%) experienced HG. During a median follow up of 26 years (25 902 036 person-years), 43 470 women died (4.4%). Women exposed to HG had a lower risk of long-term all-cause mortality compared with women without HG (crude HR 0.82; 95% CI 0.75–0.90). When adjusting for confounders, this reduction was no longer significant (adjusted HR 0.92; 95% CI 0.84–1.01). Women exposed to HG had a similar risk of cardiovascular death as women not exposed (adjusted HR 1.04; 95% CI 0.83–1.29), but a lower long-term risk of death from cancer (adjusted HR 0.86; 95% CI 0.75–0.98). Conclusion In this large population-based cohort study, HG was not associated with an increased risk of long-term all-cause mortality. Women exposed to HG had no increase in mortality due to cardiovascular disease, but had a reduced risk of death from cancer.

• Degerud, Eirik; Ystrøm, Eivind; Tambs, Kristian; Ariansen, Inger Kristine; Mørland, Jørg & Magnus, Per [Show all 8 contributors for this article] (2017). The interplay between cognitive ability, alcohol consumption, and health characteristics. Psychological Medicine. ISSN 0033-2917. 48(12), p. 2011–2022. doi: 10.1017/S0033291717003543. Full text in Research Archive
• Egeland, Grace M.; Tell, Grethe S.; Næss, Øyvind; Igland, Jannicke & Klungsøyr, Kari (2017). Association between pregravid physical activity and family history of stroke and risk of stillbirth: Population-based cohort study. BMJ Open. 7:e017034(8), p. 1–8. doi: 10.1136/bmjopen-2017-017034. Full text in Research Archive Show summary

  Objectives: To evaluate whether family history of disease and pregravid lifestyle and cardiovascular risk factors are associated with subsequent stillbirth delivery. Design: Prepregnancy cohort study. Setting: Cohort Norway regional health surveys (1994–2003) linked to Medical Birth Registry of Norway for deliveries through 2012. Participants: 13 497 singleton births (> 22 weeks gestation) in 8478 women. Main outcome measure: Risk of stillbirth evaluated by Poisson regression. Results: Mean (SD) length of follow-up was 5.5 (3.5) years. In analyses adjusting for baseline age and length of follow-up, ≥3 hours of baseline past-year vigorous physical activity per week (resulting in shortness of breath/sweating) was associated with increased risk of stillbirth compared with <1 hour/week of vigorous activity (incidence rate ratio, IRR 2.46; 95% CI 1.23 to 4.90). In contrast, baseline past-year light physical activity of ≥3 hours per week associated with reduced risk of stillbirth compared with <3 hours of light physical activity per week (IRR 0.53; 95% CI 0.30 to 0.93). A family history of stroke associated with increased risk of stillbirth delivery (IRR 2.53; 95% CI 1.06 to 6.01). Because overweight/obese women may experience shortness of breath and sweating with less physical exertion than normal weight women, a sensitivity analysis was conducted limited to women with a normal BMI (> 18.5 and <25 kg/m2). Vigorous activity of ≥3 hours per week (IRR of 4.50; 95% CI 1.72 to 11.79) and a family history of stroke (IRR of 3.81; 95% CI 1.31 to 11.07) were more strongly related to stillbirth risk among women with a normal BMI than that observed for all women combined. Established risk factors also associated with stillbirth risk. Conclusions: The study identified physical activity and family history of stroke as potential new risk factors for stillbirth delivery.

• Syse, Astri; Strand, Bjørn Heine; Næss, Øyvind; Steingrímsdóttir, Ólöf Anna & Kumar, Bernadette. N (2016). Differences in all-cause mortality: A comparison between immigrants and the host population in Norway 1990-2012. Demographic Research. ISSN 1435-9871. 34, p. 615–655. doi: 10.4054/DemRes.2016.34.22. Full text in Research Archive
• Birkemoe, Tone; Lindstedt, Heidi Elisabeth Heggen; Ottesen, Preben; Soleng, Arnulf; Næss, Øyvind & Rukke, Bjørn Arne (2016). Head lice predictors and infestation dynamics among primary school children in Norway. Family Practice. ISSN 0263-2136. 33(1), p. 23–29. doi: 10.1093/fampra/cmv081. Full text in Research Archive Show summary

  Background. Health providers need to know which measures to take and children to prioritize in order to decrease costs associated with head lice infestations. Objective. Our aim was to determine the most important predictors for head lice and identify the major drivers of an infestation outbreak in a low-prevalence area. Methods. The study was based on three datasets of head lice prevalence (retrospective, point prevalence and prospective approach) from primary school children (ages 6–12) at 12 schools in Oslo, Norway. The tested predictors were siblings with lice, individual and household characteristics as well as class and school affiliation. Self-reported monthly incidences (prospective approach) of head lice were used to evaluate infestation dynamics. Results. Infested siblings strongly increased the odds of head lice infestation of school children (odds ratio 36, 26 and 7 in the three datasets) whereas having short hair halved the odds. Household characteristics were of minor importance, and class affiliation proved more important than school affiliation. Having head lice in one school term increased the odds of an infestation in the next, but this effect diminished over time. About 97% of all self-reported infestations were noted in two consecutive months or less. Conclusions. With the exception of hair length, we have found that individual and household characteristics are of minor importance to predict head lice infestations in a low-prevalence country and that unnoticed transmissions in school classes and families are likely to be the major driver upon outbreaks.

• Egeland, Grace M.; Klungsøyr, Kari; Øyen, Nina; Tell, Grethe Seppola; Næss, Øyvind & Skjaerven, Rolv (2016). Preconception cardiovascular risk factor differences between gestational hypertension and preeclampsia: Cohort Norway study. Hypertension. ISSN 0194-911X. 67(6), p. 1173–1180. doi: 10.1161/HYPERTENSIONAHA.116.07099. Full text in Research Archive Show summary

  Preconception predictors of gestational hypertension and preeclampsia may identify opportunities for early detection and improve our understanding of the pathogenesis and life course epidemiology of these conditions. Female participants in community-based Cohort Norway health surveys, 1994 to 2003, were prospectively followed through 2012 via record linkages to Medical Birth Registry of Norway. Analyses included 13 217 singleton pregnancies (average of 1.59 births to 8321 women) without preexisting hypertension. Outcomes were gestational hypertension without proteinuria (n=237) and preeclampsia (n=429). Mean age (SD) at baseline was 27.9 years (4.5), and median follow-up was 4.8 years (interquartile range 2.6–7.8). Gestational hypertension and preeclampsia shared several baseline risk factors: family history of diabetes mellitus, pregravid diabetes mellitus, a high total cholesterol/high-density lipoprotein cholesterol ratio (>5), overweight and obesity, and elevated blood pressure status. For preeclampsia, a family history of myocardial infarction before 60 years of age and elevated triglyceride levels (≥1.7 mmol/L) also predicted risk while physical activity was protective. Preterm preeclampsia was predicted by past-year binge drinking (≥5 drinks on one occasion) with an adjusted odds ratio of 3.7 (95% confidence interval 1.3–10.8) and by past-year physical activity of ≥3 hours per week with an adjusted odds ratio of 0.5 (95% confidence interval 0.3–0.8). The results suggest similarities and important differences between gestational hypertension, preeclampsia, and preterm preeclampsia. Modifiable risk factors could be targeted for improving pregnancy outcomes and the short- and long-term sequelae for mothers and offspring.

• Kjøllesdal, Marte Karoline Råberg; Ariansen, Inger Kristine Holtermann; Mortensen, Laust Hvas; Smith, George Davey & Næss, Øyvind (2016). Educational differences in cardiovascular mortality - the role of shared family factors and cardiovascular risk factors. Scandinavian Journal of Public Health. ISSN 1403-4948. 44(8), p. 744–750. doi: 10.1177/1403494816669427. Full text in Research Archive
• Fiskå, Bendik Seth; Ariansen, Inger; Graff-Iversen, Sidsel; Tell, Grethe Seppola; Egeland, Grace M. & Næss, Øyvind (2015). Family history of premature myocardial infarction, life course socioeconomic position and coronary heart disease mortality - a Cohort of Norway (CONOR) study. International Journal of Cardiology. ISSN 0167-5273. 190, p. 302–307. doi: 10.1016/j.ijcard.2015.04.160. Full text in Research Archive
• Ariansen, Inger; Mortensen, Laust; Igland, Jannicke; Tell, Grethe Seppola; Tambs, Kristian & Graff-Iversen, Sidsel [Show all 8 contributors for this article] (2015). The educational gradient in coronary heart disease: the association with cognition in a cohort of 57 279 male conscripts. Journal of Epidemiology and Community Health. ISSN 0143-005X. 69(4), p. 322–329. doi: 10.1136/jech-2014-204597. Full text in Research Archive
• Kinge, Jonas Minet; Steingrímsdóttir, Ólöf Anna; Moe, Joakim Oliu; Skirbekk, Vegard; Næss, Øyvind & Strand, Bjørn Heine (2015). Educational differences in life expectancy over five decades among the oldest old in Norway. Age and Ageing. ISSN 0002-0729. 44(6), p. 1040–1045. doi: 10.1093/ageing/afv128. Full text in Research Archive
• Omsland, Tone Kristin; Eisman, John A.; Næss, Øyvind; Center, Jacqueline R; Gjesdal, Clara Gram & Tell, Grethe Seppola [Show all 13 contributors for this article] (2015). Educational inequalities in post-hip fracture mortality: a NOREPOS studys. Journal of Bone and Mineral Research. ISSN 0884-0431. 30(12), p. 2221–2228. doi: 10.1002/jbmr.2579. Full text in Research Archive Show summary

  Hip fractures are associated with high excess mortality. Education is an important determinant of health, but little is known about educational inequalities in post-hip fracture mortality. Our objective was to investigate educational inequalities in post-hip fracture mortality and to examine whether comorbidity or family composition could explain any association. We conducted a register-based population study of Norwegians aged 50 years and older from 2002 to 2010. We measured total mortality according to educational attainment in 56,269 hip fracture patients (NORHip) and in the general Norwegian population. Both absolute and relative educational inequalities in mortality in people with and without hip fracture were compared. There was an educational gradient in post-hip fracture mortality in both sexes. Compared with those with primary education only, the age-adjusted relative risk (RR) of mortality in hip fracture patients with tertiary education was 0.82 (95% confidence interval [CI] 0.77-0.87) in men and 0.79 (95% CI 0.75-0.84) in women. Additional adjustments for Charlson comorbidity index, marital status, and number of children did not materially change the estimates. Regardless of educational attainment, the 1-year age-adjusted mortality was three- to fivefold higher in hip fracture patients compared with peers in the general population without fracture. The absolute differences in 1-year mortality according to educational attainment were considerably larger in hip fracture patients than in the population without hip fracture. Absolute educational inequalities in mortality were higher after hip fracture compared with the general population without hip fracture and were not mediated by comorbidity or family composition. Investigation of other possible mediating factors might help to identify new targets for interventions, based on lower educational attainment, to reduce post-hip fracture mortality.

• Ariansen, Inger; Graff-Iversen, Sidsel; Stigum, Hein; Strand, Bjørn Heine; Wills, Andrew K & Næss, Øyvind (2015). Do repeated risk factor measurements influence the impact of education on cardiovascular mortality? Heart. ISSN 1355-6037. 101(23), p. 1889–1894. doi: 10.1136/heartjnl-2014-307380. Full text in Research Archive
• Du, Qing; Lian, Wu; Næss, Øyvind; Bjertness, Espen; Kumar, Bernadette. N & Shi, Shu-hua (2015). The trends in maternal mortality between 1996 and 2009 in Guizhou, China: Ethnic differences and associated factors. Journal of Huazhong University of Science and Technology. Medical Sciences. ISSN 1672-0733. 35(1), p. 140–146. doi: 10.1007/s11596-015-1403-8. Full text in Research Archive
• Igland, Jannicke; Vollset, Stein Emil; Nygård, Ottar; Sulo, Gerhard; Sulo, Enxhela & Ebbing, Marta [Show all 9 contributors for this article] (2014). Educational inequalities in 28 day and 1-year mortality after hospitalisation for incident acute myocardial infarction - A nationwide cohort study. International Journal of Cardiology. ISSN 0167-5273. 177(3), p. 874–880. doi: 10.1016/j.ijcard.2014.10.045. Full text in Research Archive
• Strand, Bjørn Heine; Steingrímsdóttir, Ólöf Anna; Grøholt, Else-Karin; Ariansen, Inger; Graff-Iversen, Sidsel & Næss, Øyvind (2014). Trends in educational inequalities in cause specific mortality in Norway from 1960 to 2010: a turning point for educational inequalities in cause specific mortality of Norwegian men after the millennium? BMC Public Health. 14. doi: 10.1186/1471-2458-14-1208. Full text in Research Archive
• Jansen, Mona Dverdal; Knudsen, Gun Peggy; Myhre, Ronny; Høiseth, Gudrun; Mørland, Jørg & Næss, Øyvind [Show all 8 contributors for this article] (2014). Genetic variants in loci 1p13 and 9p21 and fatal coronary heart disease in a Norwegian case-cohort study. Molecular Biology Reports. ISSN 0301-4851. 41(5), p. 2733–2743. doi: 10.1007/s11033-014-3096-7. Full text in Research Archive
• Claussen, Bjørgulf; Næss, Øyvind; Reime, Leif Jostein & Leyland, Alastair H (2013). Proof firm downsizing and diagnosis-specific disability pensioning in Norway. BMC Public Health. 13. doi: 10.1186/1471-2458-13-27. Full text in Research Archive Show summary

  Background We wanted to investigate if firm downsizing is related to an increased rate of disability pensions among the former employed, especially for those with musculoskeletal and psychiatric diagnoses, and for those having to leave the firm. Methods Statistics Norway provided a linked file with demographic information and all social security grants from the National Insurance Administration for 1992–2004 for all inhabitants in Norway. Our sample was aged 30–55 years in 1995, being alive, employed and not having a disability pension at the end of 2000. Downsizing was defined as percent change in number of employed per firm from 1995 to end 2000. Employment data were missing for 25.6% of the sample. Results Disability pension rates in the next four years were 25% higher for those experiencing a 30-59% downsizing than for those not experiencing a reduction of the workforce. 1-29% and 60-100% downsizing did not have this effect. Stayers following down-sizing had higher disability pension rates than leavers. What we have called complex musculoskeletal and psychiatric diagnoses were relatively most common. Conclusion Moderate downsizing is followed by a significant increase in disability pension rates in the following four years, often with complex musculoskeletal and psychiatric diagnoses.

• Næss, Øyvind; Stoltenberg, Camilla; Hoff, Dominic Anthony; Nystad, Wenche; Magnus, Per & Tverdal, Aage [Show all 7 contributors for this article] (2013). Cardiovascular mortality in relation to birth weight of children and grandchildren in 500 000 Norwegian families. European Heart Journal. ISSN 0195-668X. 34(44), p. 3427–3436. doi: 10.1093/eurheartj/ehs298. Full text in Research Archive
• Dooghabadi, Malihe Zarre; Hjortland, Håkon André; Næss, Øyvind; Lee, Kin Keung & Lande, Tor Sverre (2013). An IR-UWB Transmitter for Ranging Systems. IEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing. ISSN 1057-7130. 60(11), p. 721–725. doi: 10.1109/TCSII.2013.2281909. Full text in Research Archive
• Strand, Bjørn Heine; Langballe, Ellen Melbye; Hjellvik, Vidar; Handal, Marte; Næss, Øyvind & Knudsen, Gun Peggy [Show all 15 contributors for this article] (2013). Midlife vascular risk factors and their association with dementia deaths: Results from a Norwegian prospective study followed up for 35 years. Journal of Neurological Sciences. ISSN 1302-1664. 324(1-2), p. 124–130. doi: 10.1016/j.jns.2012.10.018. Full text in Research Archive
• Næss, Øyvind & Hoff, Dominic Anthony (2013). The Norwegian Family Based Life Course (NFLC) study: data structure and potential for public health research. International Journal of Public Health. ISSN 1661-8556. 58(1), p. 57–64. doi: 10.1007/s00038-012-0379-4. Full text in Research Archive

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• Kvalvaag, Elisabeth Myrset; Hjellvik, Vidar; Maltzahn, Niklas Nyboe; Karlstad, Øystein; Anjum, Mariam & Wisløff, Torbjørn [Show all 15 contributors for this article] (2026). Sex differences in OAC initiation for patients with incident atrial fibrillation: The Norwegian AFNOR study. Full text in Research Archive
• Maltzahn, Niklas Nyboe; Kvalvaag, Elisabeth Myrset; Hjellvik, Vidar; Anjum, Mariam; Skovlund, Eva & Wisløff, Torbjørn [Show all 14 contributors for this article] (2026). Causal effects of modifying CHA2DS2Va guidelines on incidence of ischemic stroke. Full text in Research Archive
• Kvalvaag, Elisabeth Myrset; Maltzahn, Niklas Nyboe; Hjellvik, Vidar; Anjum, Mariam; Skovlund, Eva & Wisløff, Torbjørn [Show all 17 contributors for this article] (2026). Factors associated with initiation of oral anticoagulants in atrial fibrillation. Full text in Research Archive
• Hjellvik, Vidar; Dalene, Knut Eirik; Meyer, Haakon Eduard; Larsen, Inger Kristin; Sund, Erik Reidar & Krokstad, Steinar [Show all 12 contributors for this article] (2026). Inequality in non-communicable disease occurrence. A Nationwide Norwegian Registry study – the NCDNOR project. Full text in Research Archive
• Dalene, Knut Eirik; Hjellvik, Vidar; Larsen, Inger Kristin; Meyer, Haakon Eduard; Stene, Lars Christian Mørch & Næss, Øyvind Erik [Show all 8 contributors for this article] (2026). Ulikhet i forekomst av ikke-smittsomme sykdommer - Hva er forekomsten av ikke-smittsomme sykdommer i 2023 hos ulike sosiale og demografiske grupper i den norske befolkningen for aldersgruppen 50–65 år. Full text in Research Archive
• Kjerpeseth, Lars Jøran; Hjellvik, Vidar; Ariansen, Inger; Bramness, Jørgen Gustav; Dalene, Knut Eirik & Krokstad, Steinar [Show all 12 contributors for this article] (2024). Social disparities in multimorbidity of noncommunicable diseases in Norway 2010-2020 – an emerging challenge in a single-disease-focused healthcare system. Data from the NCDNOR project. Full text in Research Archive
• Veloz, Maria Fernanda Vinueza; Næss, Øyvind Erik; Bhatta, Laxmi; Brumpton, Ben Michael & Jones, Paul Remy (2024). Estimating maternal and paternal effects of educational attainment on offspring. Full text in Research Archive
• Næss, Øyvind Erik (2024). Folkehelseutfordringer hos menn. 144(14). doi: 10.4045/tidsskr.24.0565. Full text in Research Archive
• Kjerpeseth, Lars Jøran; Hjellvik, Vidar; Ariansen, Inger; Bramness, Jørgen Gustav; Dalene, Knut Eirik & Krokstad, Steinar [Show all 11 contributors for this article] (2024). NCD multimorbidity in Norway 2010-2020 – a NCDNOR study. Full text in Research Archive
• Choi, Hye Jung; Nguyen, Huong Thu; Veloz, Maria Fernanda Vinueza; Næss, Øyvind Erik & Jones, Paul Remy (2024). Life course socioeconomic position and cardiovascular disease: The combined influence of shared family factors, cognitive ability, and risk factors. Full text in Research Archive
• Kjerpeseth, Lars Jøran; Hjellvik, Vidar; Ariansen, Inger; Bramness, Jørgen Gustav; Dalene, Knut Eirik & Krokstad, Steinar [Show all 11 contributors for this article] (2023). NCD multimorbidity in Norway 2010-2020 – a NCDNOR study. Full text in Research Archive
• Næss, Øyvind Erik; Krokstad, Steinar; Grimsgaard, Anne Sameline; Larsen, Inger Kristin; Meyer, Haakon Eduard & Nystad, Wenche (2023). Overvåkning av ikke-smittsomme sykdommer. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 143(15). doi: 10.4045/tidsskr.23.0595. Full text in Research Archive
• Berge, T.; Næss, Øyvind Erik; Wisløff, Torbjørn; Mortensen, L. H.; Skovlund, Eva & Karlstad, Øystein [Show all 17 contributors for this article] (2023). Registry tool for stroke prevention in atrial fibrillation in Norway – RegTool AFNOR. Full text in Research Archive
• Næss, Øyvind Erik (2023). Gener og ulikhet: Tvillingstudier kan feilvurdere det genetiske bidraget. Morgenbladet. ISSN 0805-3847. Full text in Research Archive
• Næss, Øyvind Erik (2023). Kortere forventet levealder hos menn skyldes ikke naturen. Full text in Research Archive
• Haram, Marit; Jangmo, Anders Andreas Krister; Koch, Elise; Plana-Ripoll, Oleguer; Bramness, Jørgen Gustav & Krokstad, Steinar [Show all 13 contributors for this article] (2023). Depression severity and life years lost. Full text in Research Archive
• Nguyen, Huong Thu; Kjøllesdal, Marte Karoline Råberg; Veloz, Maria Fernanda Vinueza; Næss, Øyvind Erik & Jones, Paul Remy (2022). The relation between average level of education among all first-degree family members and risk of cardiovascular and all-cause mortality. Full text in Research Archive
• Næss, Øyvind Erik & Jones, Paul Remy (2021). Sosiale ulikheter i helse – før, under og etter pandemien. Michael. ISSN 1893-9651. Full text in Research Archive
• Nguyen, Huong Thu; Næss, Øyvind Erik; Valberg, Morten; Page, Christian Magnus; Leblanc, Marissa Erin & Moger, Tron Anders (2021). Modelling unobserved heterogeneity by education level in cardiovascular disease mortality - A frailty analysis of Norwegian population-based health surveys. Full text in Research Archive
• Næss, Øyvind (2018). Editorial commentary: What drives trends in inequalities of cardiovascular disease? doi: 10.1016/j.tcm.2018.10.011. Full text in Research Archive
• Flaten, Trond Peder; Næss, Øyvind Erik & Bakketeig, Leiv Sigmund (2015). History of Epidemiology in Norway. Temanummer av tidsskriftet Norsk Epidemiologi, 2015, Vol. 25, No. 1-2. Norsk forening for epidemiologi. Full text in Research Archive
• Strand, Bjørn Heine; Steingrímsdóttir, Ólöf Anna; Myklestad, Ingri & Næss, Øyvind (2013). Endringer i ulikheter i dødelighet etter utdanning i Norge – en underlagsrapport om mulige forklaringer. Underlagsrapport til prosjektet Sosial ulikhet i helse: en norsk kunnskapsoversikt, Høgskolen i Oslo og Akershus, 2014. Nasjonalt folkehelseinstitutt. Full text in Research Archive

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