Per Nafstad

• Mohn, Cathrine Helene; Blix, Hege Salvesen; Brænd, Anja Maria; Nafstad, Per & Halvorsen, Jon Anders (2023). Prevalence of Isotretinoin Therapy in Adolescents and Young Adults With and Without Atopic Dermatitis: A Nationwide Prescription-based Population Study. Acta Dermato-Venereologica. ISSN 0001-5555. 103, p. 1–7. doi: 10.2340/actadv.v103.9424. Full text in Research Archive Show summary

  Although isotretinoin has anti-inflammatory and immunomodulatory properties, it can exacerbate atopic dermatitis. National estimates of the extent to which patients with atopic dermatitis are affected by severe acne and isotretinoin tolerability are lacking. The aim of this study is to investigate isotretinoin therapy in patients with atopic dermatitis and to compare the nationwide prevalence with individuals without atopic dermatitis. All Norwegian residents were followed for 17 years until age 20–22 years in 2020. Approximately 28% of patients with atopic dermatitis had been treated for acne, and 8% had received isotretinoin before age 23 years. In those over 17 years old, significantly more patients with atopic dermatitis were treated with isotretinoin than those without. At age 22 years, 2.21% (95% confidence interval 1.92–2.49) of patients with atopic dermatitis were treated with isotretinoin, compared with 1.55% (95% confidence interval 1.44–1.65) of those without, representing 42.8% (1.43; 95% confidence interval 1.24–1.65) higher use in patients with atopic dermatitis. Patients who received long-term treatment (probable severe atopic dermatitis) tolerated isotretinoin similarly to patients who received short-term treatment (probable mild atopic dermatitis). There was significantly higher use of topical corticosteroids during isotretinoin therapy in patients with atopic dermatitis. Conclusively, severe acne (isotretinoin therapy) was associated with atopic dermatitis at the population level in young adults.

• Mohn, Cathrine Helene; Blix, Hege Salvesen; Brænd, Anja Maria; Nafstad, Per; Nygård, Ståle & Halvorsen, Jon Anders (2022). Treatment Patterns of Atopic Dermatitis Medication in 0–10-Year-Olds: A Nationwide Prescription-Based Study. Dermatology and Therapy. ISSN 2193-8210. 12(7), p. 1639–1657. doi: 10.1007/s13555-022-00754-6. Full text in Research Archive Show summary

  Introduction The literature on treatment patterns for paediatric atopic dermatitis (AD) is scarce and is rarely based on real-world data. Using national registers, we sought to establish up-to-date, population-based prevalence estimates, predictors of risk and disease burden and a comprehensive overview of treatment patterns and course for paediatric patients with AD. Methods Dispensed prescriptions for the entire Norwegian child population aged 0–10 years from 2014 to 2020 were analysed. Results There were 176,458 paediatric patients with AD. Of these, 99.2% received topical corticosteroids, 5.1% received topical calcineurin inhibitors, 37.1% received potent topical corticosteroids and 2.1% received systemic corticosteroids. Of the 59,335 live births in Norway (2014), 14,385 [24.8%; 95% confidence interval (CI) 24.5–25.1] paediatric patients were treated for AD before the age of 6 years, and of these, only 934 (6.5%; 95% CI 6.1–6.9) received medication annually for 5 years or more. Compared with girls, 17.9% (95% CI 6.5–27.9) more boys were treated for at least 5 years, receiving 6.4% (95% CI 1.2–11.3) more potent topical corticosteroids and 12.4% (95% CI 6.5–18.0) more were treated for skin infections. Compared with patients with late-onset treatment, 18.9% (95% CI 7.5–29.0) more paediatric patients with early-onset treatment were still receiving treatment at 5 years of age, 15.7% (95% CI 7.1–23.4) more paediatric patients received potent topical corticosteroids and 44.4% (95% CI 36.5–51.2) more paediatric patients were treated for skin infections. Conclusion Most paediatric patients were treated for a mild disease for a limited period. Although the prevalence of AD is higher at a younger age, these paediatric patients were the least likely to receive potent topical corticosteroids. Male sex and early-onset AD are associated with and are potential predictors of long-term treatment and treatment of potent topical corticosteroids, antihistamines and skin infections, which may have clinical utility for personalised prognosis, healthcare planning and future AD prevention trials.

• Håheim, Lise Lund; Schwarze, Per Everhard; Thelle, Dag Steinar; Nafstad, Per; Rønningen, Kjersti Skjold & Olsen, Ingar (2020). Low levels of antibodies for the oral bacterium Tannerella forsythia predict cardiovascular disease mortality in men with myocardial infarction: A prospective cohort study - PubMed. Medical Hypotheses. ISSN 0306-9877. doi: 10.1016/j.mehy.2020.109575. Full text in Research Archive Show summary

  Antibody levels to periodontal pathogens in prediction of cardiovascular disease (CVD) mortality were explored using data from a health survey in Oslo in 2000 (Oslo II-study) with 12 1/2 years follow-up. IgG antibodies to four common periodontal pathogens; Tannerella forsythia (TF), Porphyromonas gi …

• Rantala, Aino K.; Magnus, Maria Christine; Karlstad, Øystein; Stigum, Hein; Håberg, Siri Eldevik & Nafstad, Per [Show all 8 contributors for this article] (2020). Is the association of early day care attendance with childhood asthma explained by underlying susceptibility? Epidemiology. ISSN 1044-3983. p. 451–458. doi: 10.1097/EDE.0000000000001163. Full text in Research Archive
• 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.

• Håheim, Lise Lund; Schwarze, Per Everhard; Thelle, Dag Steinar; Nafstad, Per; Rønningen, Kjersti Skjold & Olsen, Ingar (2020). Low levels of antibodies for the oral bacterium Tannerella forsythia predict cardiovascular disease mortality in men with myocardial infarction: A prospective cohort study. Medical Hypotheses. ISSN 0306-9877. 138. doi: 10.1016/j.mehy.2020.109575. Full text in Research Archive Show summary

  Antibody levels to periodontal pathogens in prediction of cardiovascular disease (CVD) mortality were explored using data from a health survey in Oslo in 2000 (Oslo II-study) with 12 1/2 years follow-up. IgG antibodies to four common periodontal pathogens; Tannerella forsythia (TF), Porphyromonas gingivalis (PG), and Treponema denticola (TD) all termed collectively the “red complex”, and Aggregatibacter actinomycetemcomitans (AA) were analysed. The study sample consisted of 1172 men drawn from a cohort of 6,530 men who participated in the Oslo II-study, where they provided information on medical and dental history. Of the study sample, 548 men had reported prior myocardial infarction (MI) at baseline whereas the remaining 624 men were randomly drawn from the ostensibly healthy participants for comparative analyses. Dental anamnestic information included tooth extractions and oral infections. An inverse relation was found for trend by the quartile risk level of TF predicting CVD mortality, p-value for trend = 0.017. Comparison of the first to fourth quartile of TF antibodies resulted in hazard ratio (HR) = 1.82, 95% confidence interval 1.12–2.94, p = 0.015, adjusted for age, education, diabetes, daily smoking, and systolic blood pressure. Specificity comparing decile 1 to deciles 2–10 of TF predicting mortality was 92.3%. We found an increased HR by low levels of antibodies to the bacterium T. forsythia predicting CVD mortality in a 12 ½ years follow-up in persons who had experienced an MI but not among non-MI men. This novel finding constitutes a plausible causal link between oral infections and CVD mortality.

• Melbye, Hasse; Helgeland, Jon; Karlstad, Øystein; Ariansen, Inger; Langhammer, Arnulf & Wisløff, Torbjørn [Show all 8 contributors for this article] (2020). Is the disease burden from COPD in Norway falling off? A study of time trends in three different data sources. The International Journal of Chronic Obstructive Pulmonary Disease. ISSN 1176-9106. 15, p. 323–334. doi: 10.2147/COPD.S235106. Full text in Research Archive Show summary

  Background: Less smoking should lead to fewer COPD cases. We aimed at estimating time trends in the prevalence and burden of COPD in Norway from 2001 to 2017. Methods: We used pre-bronchodilator spirometry and other health data from persons aged 40– 84 years in three surveys of the Tromsø Study, 2001– 2002, 2007– 2008 and 2015– 2016. We applied spirometry lower limits of normal (LLN) according to Global Lung Initiative 2012. Age-standardized prevalence was determined. We defined COPD as FEV1/FVC1 Results: In the Tromsø Study, the age-standardized prevalence of daily smoking dropped from 29.9% to 14.1% among women and from 31.4% to 12.8% among men (P< 0.0001). The age-standardized prevalence of COPD dropped from 7.6% to 5.6% among women (P=0.2) and from 7.3% to 5.6% among men (P=0.003) and of moderate to severe COPD from 5.2% to 2.7% among women (P=0.0003) and from 4.6% to 3.2% among men (P=0.0008). Among men, the yearly age-standardized prevalence of hospitalization due to COPD exacerbation decreased from 3.6 to 3.0 per 1000 inhabitants aged 40– 84 years (P<0.0001). Correspondingly, dispensing oral corticosteroids or/and antibiotics for COPD exacerbations dropped from 6.6 to 5.8 per 1000 (P<0.0001), while dispensing maintenance treatment increased (P<0.0001). Conclusion: COPD morbidity decreased between 2001 and 2017, which might partly be due to less smoking. The drop in smoking prevalence gives promise of a further substantial decrease in the coming decades.

• 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.

• Evandt, Jorunn; Skurtveit, Svetlana; Oftedal, Bente Margaret; Krog, Norun Hjertager; Nafstad, Per & Skovlund, Eva [Show all 8 contributors for this article] (2019). Agreement between self-reported and registry-based use of sleep medications and tranquilizers. Pharmacoepidemiology and Drug Safety. ISSN 1053-8569. 28(10), p. 1336–1343. doi: 10.1002/pds.4854. Full text in Research Archive Show summary

  Purpose The purpose of the present study was to assess the agreement between self‐reported use of sleep medications and tranquilizers and dispensed hypnotics and anxiolytics. Methods Self‐reported medication use was obtained from the population‐based survey Health and Environment in Oslo (HELMILO) (2009‐2010) (n = 13 019). Data on dispensed hypnotics and anxiolytics were obtained from the Norwegian Prescription Database (NorPD). As measures of validity, we calculated sensitivity and specificity using both self‐reports and prescription records as the reference standard. Furthermore, we calculated Cohen's kappa. Current self‐reported medication use was compared with prescription data in time windows of both 100 and 200 days preceding questionnaire completion. Results The highest sensitivity was observed for current sleep medication use in the 100‐day time window (sensitivity = 0.76, 95% confidence interval [CI]: 0.74, 0.79) when using prescription records as the reference standard. Sensitivity was generally lower for tranquilizers compared with sleep medications. Cohen's kappa showed the highest agreement for the 200‐day time window with substantial agreement for sleep medications (kappa = 0.64; 95% CI: 0.62, 0.67) and moderate agreement for tranquilizers (kappa = 0.45; 95% CI: 0.41, 0.48). Conclusions The present study suggests moderate to substantial agreement between self‐reported use of sleep medications and tranquilizers and dispensed drugs in a general adult population. The magnitude of agreement varied according to drug category and time window. Since self‐reported and registry‐based use of these drug classes does not match each other accurately, limitations of each data source should be considered when such medications are applied as the exposure or outcome in epidemiologic studies.

• Magnus, Maria Christine; Karlstad, Øystein; Parr, Christine Louise; Page, Christian; Nafstad, Per & Magnus, Per [Show all 10 contributors for this article] (2019). Maternal history of miscarriages and measures of fertility in relation to childhood asthma. Thorax. ISSN 0040-6376. 74(2), p. 106–113. doi: 10.1136/thoraxjnl-2018-211886. Full text in Research Archive Show summary

  Background: it remains unclear what underlies the greater risk of asthma reported among children conceived by assisted reproductive technologies (art). Objective: Our aim was to clarify the role of parental subfertility and unmeasured confounding on the association between art and childhood asthma, and to examine the possibility for common mechanisms underlying parental subfertility and miscarriages influencing asthma pathogenesis. Methods: We used data from national norwegian health registries (n=474 402) and the norwegian Mother and child cohort Study (MoBa) (n=75 797). We used log-linear regression to estimate overall associations, and fixed-effects logistic regression to estimate associations within siblings. Results: ART offspring had greater asthma risk, the adjusted relative risk (arr) was 1.20 (95% ci 1.09 to 1.32) in the registry-based cohort, and 1.42 (95% ci 1.14 to 1.76) in MoBa. the sibling analysis yielded similar associations, although the ci included the null value. the elevated asthma risk among art offspring was attenuated when they were compared with spontaneously conceived offspring with time to conception >12 months, arr 1.22 (95% ci 0.95 to 1.57). asthma risk also increased with maternal history of early miscarriages (≤12 weeks), with an arr of 1.07 (95% ci 1.03 to 1.11) for one, arr 1.18 (95% ci 1.10 to 1.26) for two and arr 1.24 (95% ci 1.12 to 1.37) for three or more. Conclusion: Our findings indicate that both parental subfertility and characteristics related to the art procedure itself might increase offspring asthma risk, although this needs to be confirmed in future studies, and further suggest that common mechanisms underlying parental subfertility and recurrent miscarriages might influence offspring asthma pathogenesis.

• Håheim, Lise Lund; Nafstad, Per; Schwarze, Per Everhard; Olsen, Ingar; Rønningen, Kjersti Skjold & Thelle, Dag Steinar (2019). Oral health and cardiovascular disease risk factors and mortality of cerebral haemorrhage, cerebral infarction and unspecified stroke in elderly men: A prospective cohort study. Scandinavian Journal of Public Health. ISSN 1403-4948. doi: 10.1177/1403494819879351. Full text in Research Archive
• 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.

• Magnus, Maria Christine; Wright, Rosalind J.; Røysamb, Espen; Parr, Christine Louise; Karlstad, Øystein & Page, Christian [Show all 10 contributors for this article] (2018). Association of Maternal Psychosocial Stress with Increased Risk of Asthma Development in Offspring. American Journal of Epidemiology. ISSN 0002-9262. 187(6), p. 1199–1209. doi: 10.1093/aje/kwx366. Full text in Research Archive Show summary

  Prenatal maternal psychosocial stress might influence childhood asthma development. Evaluating paternal psychosocial stress and conducting a sibling comparison could provide further insight into the role of unmeasured confounding. We examined the associations of parental psychosocial stress during and after pregnancy with asthma at 7 years in the Norwegian Mother and Child Cohort Study (n = 63,626). Measures of psychosocial stress included lifetime major depressive symptoms, current anxiety/depression symptoms, use of antidepressants, anxiolytics and/or hypnotics, life satisfaction, relationship satisfaction, work stress and social support. Childhood asthma was associated with maternal lifetime major depressive symptoms, adjusted relative risk (aRR) = 1.19 (95% CI: 1.09, 1.30), in addition to symptoms of anxiety/depression during pregnancy, aRR = 1.17 (95% CI: 1.06, 1.29), and 6 months after delivery, aRR = 1.17 (95% CI: 1.07, 1.28). Maternal negative life events during pregnancy, aRR = 1.10 (95% CI: 1.06, 1.13), and 6 months after delivery, aRR = 1.14 (95% CI: 1.11, 1.18), were also associated with asthma. These associations were not replicated when evaluated within sibling groups. There were no associations with paternal psychosocial stress. In conclusion, maternal anxiety/depression and negative life events was associated with offspring asthma, but this might be explained by unmeasured maternal background characteristics that remain stable across deliveries.

• Parr, Christine Louise; Magnus, Maria Christine; Karlstad, Øystein; Holvik, Kristin; Lund-Blix, Nicolai Andre & Haugen, Margaretha [Show all 12 contributors for this article] (2018). Vitamin A and D intake in pregnancy, infant supplementation, and asthma development: The Norwegian Mother and Child Cohort. American Journal of Clinical Nutrition. ISSN 0002-9165. 107(5), p. 789–798. doi: 10.1093/ajcn/nqy016. Full text in Research Archive Show summary

  Background Western diets may provide excess vitamin A, which is potentially toxic and could adversely affect respiratory health and counteract benefits from vitamin D. Objective The aim of this study was to examine child asthma at age 7 y in relation to maternal intake of vitamins A and D during pregnancy, infant supplementation with these vitamins, and their potential interaction. Design We studied 61,676 school-age children (born during 2002–2007) from the Norwegian Mother and Child Cohort with data on maternal total (food and supplement) nutrient intake in pregnancy (food-frequency questionnaire validated against biomarkers) and infant supplement use at age 6 mo (n = 54,142 children). Linkage with the Norwegian Prescription Database enabled near-complete follow-up (end of second quarter in 2015) for dispensed medications to classify asthma. We used log-binomial regression to calculate adjusted RRs (aRRs) for asthma with 95% CIs. Results Asthma increased according to maternal intake of total vitamin A [retinol activity equivalents (RAEs)] in the highest (≥2031 RAEs/d) compared with the lowest (≤779 RAEs/d) quintile (aRR: 1.21; 95% CI: 1.05, 1.40) and decreased for total vitamin D in the highest (≥13.6 µg/d) compared with the lowest (≤3.5 µg/d) quintile (aRR: 0.81; 95% CI: 0.67, 0.97) during pregnancy. No association was observed for maternal intake in the highest quintiles of both nutrients (aRR: 0.99; 95% CI: 0.83, 1.18) and infant supplementation with vitamin D or cod liver oil. Conclusions Excess vitamin A (≥2.5 times the recommended intake) during pregnancy was associated with increased risk, whereas vitamin D intake close to recommendations was associated with a reduced risk of asthma in school-age children. No association for high intakes of both nutrients suggests antagonistic effects of vitamins A and D. This trial was registered at http://www.clinicaltrials.gov as NCT03197233. © 2018 American Society for Nutrition. This work is written by (a) US Government employee(s) and is in the public domain in the US.

• 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
• Mohn, Cathrine Helene; Blix, Hege Salvesen; Halvorsen, Jon Anders; Nafstad, Per; Valberg, Morten & Lagerløv, Per (2018). Incidence Trends of Atopic Dermatitis in Infancy and Early Childhood in a Nationwide Prescription Registry Study in Norway. JAMA Network Open. 1(7). doi: 10.1001/jamanetworkopen.2018.4145. Full text in Research Archive Show summary

  Importance With increasing prevalence of atopic dermatitis (AD) and its manifestation in most countries, together with the supporting evidence of the progression to other atopic phenotypes, AD has developed into a worldwide public health concern. The presence of the disease of has increased since the 1950s, but some recent studies suggest a stationary or decreasing trend. Objective To analyze a nationwide health register based on prescription data to determine the incidence rate (IR) of AD in an entire pediatric population. Design, Setting, and Participants All children resident in Norway younger than 6 years from January 1, 2009, through December 31, 2015, were included in this cohort study. Medical diagnoses and disease-specific medications were used as a proxy for identifying children with AD in this population-based prescription registry study. The prescription study was terminated in 2016. The total number of 295 286 disease-specific prescriptions was analyzed from August 2016 through December 2017. The hypothesis was formulated before, during, and after the data collection. Main Outcomes and Measures All children with a medical diagnosis of AD or eczema based on at least 2 prescriptions of topical corticosteroids or at least 1 prescription of topical calcineurin inhibitors. Incidence rates per person-year (PY) and IR ratios were calculated. Results A total of 295 286 disease-specific prescriptions were dispensed to 122 470 children, of whom 63 460 had AD and 56 009 (88.3%) had reimbursed prescriptions and associated AD diagnoses. The annual Norwegian study population (aged <6 years) increased from 357 451 children in 2009 to 373 954 in 2015. The overall IR increased from 0.028 per PY (95% CI, 0.028-0.029 per PY) in 2009 to 0.034 per PY (95% CI, 0.033-0.035 per PY) in 2014. For children younger than 1 year, the IR increased from 0.052 per PY (95% CI, 0.050-0.053 PY) in 2009 to 0.073 per PY (95% CI, 0.071-0.075 per PY) in 2014. In this age group, the IR was 53% higher in boys compared with girls (IR ratio, 1.53; 95% CI, 1.49-1.57; P < .001). The incidence proportion before the age of 6 years was 17.4% (95% CI, 17.2%-17.7%). The primary seasons for the onset of AD were winter and spring. Conclusions and Relevance This nationwide study suggests an increase in the IR of pediatric AD, especially among children younger than 1 year. This study’s findings suggest that increase occurred with a higher IR during winter and spring seasons. Atopic dermatitis had an earlier onset in boys than in girls. During the study period, more than 1 in 6 children younger than 6 years had, at some point, been affected by AD.

• Nafstad, Per (2018). Kronisk obstruktiv lungesykdom (kols) i Norge. In Grøholt, Else Karin; Bøhler, Linn & Hånes, Hanna (Ed.), Folkehelserapporten - Helsetilstanden i Norge. Folkehelseinstituttet. Full text in Research Archive
• Nafstad, Per; Granum, Berit; Nystad, Wenche & Nygaard, Unni Cecilie (2018). Astma og allergi. In Grøholt, Else Karin; Bøhler, Linn & Hånes, Hanna (Ed.), Folkehelserapporten - Helsetilstanden i Norge. Folkehelseinstituttet. Full text in Research Archive
• Mohn, Cathrine Helene; Halvorsen, Jon Anders; Salvesen, Hege Blix; Lagerløv, Per; Nafstad, Per & Valberg, Morten (2018). Incidence Trends of Atopic Dermatitis in Infancy and Early Childhood in a Nationwide Prescription Registry Study in Norway. JAMA Network Open. doi: 10.1001/jamanetworkopen.2018.4145. Full text in Research Archive
• Evandt, Jorunn; Oftedal, Bente Margaret; Krog, Norun Hjertager; Nafstad, Per; Schwarze, Per E & Aasvang, Gunn Marit (2017). A Population-Based Study on Nighttime Road Traffic Noise and Insomnia. Sleep. ISSN 0161-8105. 40(2). doi: 10.1093/sleep/zsw055. Full text in Research Archive
• Giorgis-Allemand, Lise; Pedersen, Marie; Bernard, Claire; Aguilera, Inmaculada; Beelen, Rob M.J. & Chatzi, Leda [Show all 49 contributors for this article] (2017). The influence of meteorological factors and atmospheric pollutants on the risk of preterm birth. American Journal of Epidemiology. ISSN 0002-9262. 185(4), p. 247–258. doi: 10.1093/aje/kww141. Full text in Research Archive Show summary

  Atmospheric pollutants and meteorological conditions are suspected to be causes of preterm birth. We aimed to characterize their possible association with the risk of preterm birth (defined as birth occurring before 37 completed gestational weeks). We pooled individual data from 13 birth cohorts in 11 European countries (71,493 births from the period 1994-2011, European Study of Cohorts for Air Pollution Effects (ESCAPE)). City-specific meteorological data from routine monitors were averaged over time windows spanning from 1 week to the whole pregnancy. Atmospheric pollution measurements (nitrogen oxides and particulate matter) were combined with data from permanent monitors and land-use data into seasonally adjusted land-use regression models. Preterm birth risks associated with air pollution and meteorological factors were estimated using adjusted discrete-time Cox models. The frequency of preterm birth was 5.0%. Preterm birth risk tended to increase with first-trimester average atmospheric pressure (odds ratio per 5-mbar increase = 1.06, 95% confidence interval: 1.01, 1.11), which could not be distinguished from altitude. There was also some evidence of an increase in preterm birth risk with first-trimester average temperature in the-5 degrees C to 15 degrees C range, with a plateau afterwards (spline coding, P = 0.08). No evidence of adverse association with atmospheric pollutants was observed. Our study lends support for an increase in preterm birth risk with atmospheric pressure.

• Gonggalanzi, ?; Labasangzhu, X; Bjertness, Espen; Wu, Tianyi; Stigum, Hein & Nafstad, Per (2017). Acute mountain sickness, arterial oxygen saturation and heart rate among Tibetan students who reascend to Lhasa after 7 years at low altitude: A prospective cohort study. BMJ Open. 7(7). doi: 10.1136/bmjopen-2017-016460. Full text in Research Archive Show summary

  Objectives The aim of the present study was to estimate the incidence of acute mountain sickness (AMS) and address the changes in arterial oxygen saturation (SaO2) and heart rate (HR) in native Tibetans who reascend to the high-altitude city of Lhasa (3658 m) after a 7-year stay at low altitude. Methods We followed two cohorts of students aged 17–21 years (859 Native Tibetan and 801 Han Chinese), travelling from lowland China until 3 days after their arrival in highland city of Lhasa. Questionnaire information of the symptoms of AMS using the Lake Louise Scoring System, resting SaO2 and HR were assessed both before leaving the lowland and after arriving in Lhasa. Linear regression was performed to compare changes in SaO2 and HR levels from low to high altitude in Tibetan and Han Chinese. Results New cases of AMS occurred in only 1.2% (95% CI 0.4% to 2.0%) of the Tibetan students who came to Lhasa by train compared with 32.7% (95% CI 28.0% to 37.3%) and 42.9% (95% CI 38.0% to 47.7%) of the Han Chinese students who came to Lhasa by train and by air, respectively. Tibetan students had less changes in SaO2 (−2.95 percentage points, 95% CI −3.24% to −2.65%) and HR (10.89 beats per minute (bpm), 95% CI 9.62 to 12.16 bpm) from low to high altitude compared with Han Chinese students, although measurements did not differ between the two groups when measured at low altitude. Conclusions Healthy Tibetans are mostly protected against AMS and primarily maintain their good adaptation to high altitude, even after a long period of stay at low altitude.

• Parr, Christine Louise; Magnus, Maria Christine; Karlstad, Øystein; Haugen, Alice Margaretha; Refsum, Helga & Ueland, Per Magne [Show all 11 contributors for this article] (2017). Maternal folate intake during pregnancy and childhood asthma in a population-based cohort. American Journal of Respiratory and Critical Care Medicine. ISSN 1073-449X. 195(2), p. 221–228. doi: 10.1164/rccm.201604-0788OC. Full text in Research Archive
• Evandt, Jorunn; Oftedal, Bente Margaret; Krog, Norun Hjertager; Skurtveit, Svetlana; Nafstad, Per & Schwarze, Per E [Show all 9 contributors for this article] (2017). Road traffic noise and registry based use of sleep medication. Environmental health. 16. doi: 10.1186/s12940-017-0330-5. Full text in Research Archive Show summary

  Background Road traffic noise has been associated with adverse health effects including sleep disturbances. Use of sleep medication as an indicator of sleeping problems has rarely been explored in studies of the effects of traffic noise. Furthermore, using registry data on sleep medications provides an opportunity to study the effects of noise on sleep where attribution of sleep problems to noise is not possible. Methods We used questionnaire data from the population-based study Health and Environment in Oslo (HELMILO) (2009–10) (n = 13,019). Individual data on sleep medications was obtained from the Norwegian Prescription Database (NorPD). Noise levels (L night) were modeled for the most exposed façade of the building at each participant’s home address. Logistic regression models adjusted for potential confounders were used to analyze the association between traffic noise and sleep medication use both for one whole year and for the summer season. The results were reported as changes in the effect estimate per 5 decibel (dB) increase in noise level. Results We observed no association between traffic noise and sleep medication use during one year [odds ratio (OR) = 1.00; 95% confidence interval (CI): 0.96, 1.04]. For sleep medication use in the summer season, there was a positive, however non-significant association (OR = 1.04; 95% CI: 0.99, 1.10). Among individuals sleeping with the bedroom window open, the association increased slightly and was borderline statistically significant (OR = 1.06; 95% CI: 1.00, 1.12). Conclusions We found no evidence of an association between traffic noise and sleep medication use during one year. However, for the summer season, there was some suggestive evidence of an association. These findings indicate that season may play a role in the association between traffic noise and sleep, possibly because indoor traffic noise levels are likely to be higher during summer due to more frequent window opening. More studies are, however, necessary in order to confirm this.

• Madsen, Christian; Håberg, Siri Eldevik; Magnus, Maria Christine; Aamodt, Geir; Stigum, Hein & London, Stephanie J. [Show all 8 contributors for this article] (2017). Pregnancy exposure to air pollution and early childhood respiratory health in the Norwegian Mother and Child Cohort Study (MoBa). BMJ Open. 7(12). doi: 10.1136/bmjopen-2016-015796. Full text in Research Archive Show summary

  Objectives: It is unclear whether maternal air pollution exposure during pregnancy induces changes in the developing respiratory system of a child and whether it has consequences for respiratory health in early childhood. We investigated associations between exposure to moderate levels of air pollution during pregnancy and early childhood lower respiratory tract infections (LRTI) and wheezing. Methods: This study used a subgroup of 17 533 participants in the Norwegian Mother and Child Cohort Study. Air pollution levels at residential addresses were estimated using land use regression models, and backextrapolated to the period of each pregnancy. Information on LRTI and wheezing and lifestyle factors was collected from questionnaires completed by mothers during pregnancy and when the child was 6 and 18 months of age. Results: Moderate mean levels of NO2 (13.6 μg/m3, range 0.01–60.4) exposure at residential address during pregnancy were not statistically associated with LRTI and wheezing. No association was found per 10 μg/m3 change in NO2 exposure and LRTI before the age of 6 months (adjusted risk ratio (RR) 0.99; 95% CI 0.84 to 1.17), or between 6 and 18 months of age (adjusted RR 1.05; 95% CI 0.94 to 1.16). Similarly, we found no association per 10 μg/m3 change in NO2 exposure and wheezing between 6 and 18 months of age (adjusted RR 1.02; 95% CI 0.97 to 1.07). Conclusions: There were no statistically significant associations for moderate levels of pregnancy NO2 exposure and respiratory health outcomes during early childhood in overall analyses.

• Madsen, Christian; Håberg, Siri Eldevik; Aamodt, Geir; Stigum, Hein; Magnus, Per & London, Stephanie J. [Show all 8 contributors for this article] (2017). Preeclampsia and hypertension during pregnancy in areas with relatively low levels of traffic air pollution. Maternal and Child Health Journal. ISSN 1092-7875. 22(4), p. 512–519. doi: 10.1007/s10995-017-2417-6. Full text in Research Archive
• Raaschou-Nielsen, O; Beelen, R; Wang, M; Hoek, G; Andersen, Z J & Hoffmann, B [Show all 54 contributors for this article] (2016). Particulate matter air pollution components and risk for lung cancer. Environment International. ISSN 0160-4120. 87, p. 66–73. doi: 10.1016/j.envint.2015.11.007. Full text in Research Archive
• Gonggalanzi, X; Labasangzhu, X; Nafstad, Per; Stigum, Hein; Wu, Tianyi & Haldorsen, Øyvind Drejer [Show all 8 contributors for this article] (2016). Acute mountain sickness among tourists visiting the high-altitude city of Lhasa at 3658 m above sea level: A cross-sectional study. Archives of Public Health. ISSN 0778-7367. 74. doi: 10.1186/S13690-016-0134-Z. Full text in Research Archive Show summary

  Background Traveling to Tibet implies a risk for developing acute mountain sickness (AMS), and the size of this problem is likely increasing due to the rising number of tourists. No previous study on AMS has been conducted among the general tourist population in Tibet. Thus, the aim of this study was to estimate the prevalence and determinants of AMS in a large tourist population visiting Lhasa. Methods A sample of 2385 tourists was recruited from seven randomly selected hotels in Lhasa between June and October 2010. Within three days of their first arrival, the participants filled in a questionnaire based on the Lake Louise Scoring System (LLSS) about AMS-related symptoms and potential contributing factors. AMS was defined as the presence of headache and a cumulative Lake Louise Score ≥4. After estimating the prevalence of AMS, a Log-Binomial Model was applied to analyse the relationship between AMS and selected risk factors. Results The prevalence of AMS was 36.7 % (95 % CI: 34.6–38.7 %) and was not dependent on tourists’ country of origin. Among the participants who developed AMS, 47.6 % reported that they experienced symptoms within the first 12 h after arriving in Lhasa, and 79.0 % reported that they had to reduce their activity level. A poor or average health condition (adjusted PR 1.63, 95 % CI 1.38–1.93), an age below 55 years (adjusted PR 1.29, 95 % CI 1.04–1.60), a rapid ascent to Lhasa (adjusted PR 1.17, 95 % CI 1.02–1.34) were independent AMS risk factors, while smoking (adjusted PR 0.75, 95 % CI 0.59–0.96) and pre-exposure to high altitude (adjusted PR 0.71, 95 % CI 0.60–0.84) reduced the risk of AMS. Conclusions AMS is commonly experienced by tourists visiting Lhasa Tibet, and often affects their activities. The tourists’ country of origin did not seem to affect their risk of AMS, and their age was inversely related to AMS. Subjects planning to visit a high-altitude area should be prepared for experiencing AMS-related problems, and consider preventive measures such as pre-exposure or a gradual ascent to high altitudes.

• Magnus, Maria Christine; Karlstad, Øystein; Midttun, Øivind; Håberg, Siri Eldevik; Tunheim, Gro & Parr, Christine Louise [Show all 11 contributors for this article] (2016). Maternal plasma total neopterin and kynurenine/tryptophan levels during pregnancy in relation to asthma development in the offspring. Journal of Allergy and Clinical Immunology. ISSN 0091-6749. 138(5), p. 1319–1325.e4. doi: 10.1016/j.jaci.2016.02.032. Full text in Research Archive
• Panasevich, Sviatlana; Håberg, Siri Eldevik; Aamodt, Geir; London, Stephanie J; Stigum, Hein & Nystad, Wenche [Show all 7 contributors for this article] (2016). Association between pregnancy exposure to air pollution and birth weight in selected areas of Norway. Archives of Public Health. ISSN 0778-7367. 74. doi: 10.1186/s13690-016-0138-8. Full text in Research Archive Show summary

  Background Exposure to air pollution has adverse effects on cardiopulmonary health of adults. Exposure to air pollution in pregnancy may affect foetal development. However, the evidence of such effect remains inconsistent. We investigated the effects of exposure to air pollution during pregnancy on birth outcomes. Methods This study, based within the Norwegian Mother and Child Cohort Study (MoBa), includes 17,533 participants living in the two largest cities in Norway: Oslo and Bergen, and their two surrounding counties: Akershus and Hordaland. Air pollution levels at residential addresses were estimated using land use regression models and back-extrapolated to the period of each pregnancy using continuous monitoring station data. Birth outcomes were birth weight, low birth weight, gestational age, and preterm delivery obtained from the Medical Birth Registry of Norway. Information on lifestyle factors was collected from MoBa questionnaires completed by mothers during pregnancy. Linear and logistic regression models were used to analyse the associations between pregnancy NO2 exposure and birth outcomes. Results We found a statistically significant negative association between pregnancy exposure to NO2 and birth weight −43.6 (95%CI −55.8 to −31.5) g per 10 μg/m3 NO2. However, after adjusting for either area or the combination of parity and maternal weight, no substantive effects of air pollution exposure were evident. Conclusions Exposure to air pollution during pregnancy was associated with decrease in birth weight, but area-related and lifestyle factors attenuated this association. We found no statistically significant associations of air pollution exposure with gestational age, low birth weight or preterm delivery.

• Rosness, Tor Atle; Strand, Bjørn Heine; Bergem, Astrid Liv Mina; Nafstad, Per; Langballe, Ellen Melbye & Engedal, Knut [Show all 8 contributors for this article] (2016). Association of psychological distress late in life and dementia-related mortality. Aging & Mental Health. ISSN 1360-7863. 20(6), p. 603–610. doi: 10.1080/13607863.2015.1031639. Full text in Research Archive
• Magnus, Maria Christine; Karlstad, Øystein; Håberg, Siri Eldevik; Nafstad, Per; Smith, George Davey & Nystad, Wenche (2016). Prenatal and infant paracetamol exposure and development of asthma: The Norwegian Mother and Child Cohort Study. International Journal of Epidemiology. ISSN 0300-5771. 45(2), p. 512–522. doi: 10.1093/ije/dyv366. Full text in Research Archive
• Magnus, Maria Christine; Håberg, Siri Eldevik; Magnus, Per; Engeland, Anders; Nafstad, Per & Karlstad, Øystein [Show all 7 contributors for this article] (2016). Pre-eclampsia and childhood asthma. European Respiratory Journal. ISSN 0903-1936. 48(6), p. 1622–1630. doi: 10.1183/13993003.00673-2016. Full text in Research Archive
• Magnus, Maria Christine; Håberg, Siri Eldevik; Karlstad, Øystein; Nafstad, Per; London, Stephanie J & Nystad, Wenche (2015). Grandmother's smoking when pregnant with the mother and asthma in the grandchild: the Norwegian Mother and Child Cohort Study. Thorax. ISSN 0040-6376. 70(3), p. 237–243. doi: 10.1136/thoraxjnl-2014-206438. Full text in Research Archive
• Aarhus, Lisa; Tambs, Kristian; Nafstad, Per; Bjørgan, Eskil & Engdahl, Bo Lars (2015). Childhood sensorineural hearing loss: effects of combined exposure with aging or noise exposure later in life. European Archives of Oto-Rhino-Laryngology. ISSN 0937-4477. doi: 10.1007/s00405-015-3649-y. Full text in Research Archive
• Yangzong, Yangzong; Berntsen, Sveinung; Andersen, Lars Bo; Stigum, Hein; Nafstad, Per & Bjertness, Espen [Show all 8 contributors for this article] (2015). Anthropometric measures of 9-to 10-year-old native tibetan children living at 3700 and 4300m above sea level and han Chinese living at 3700m. Medicine. ISSN 0025-7974. 94(42). doi: 10.1097/MD.0000000000001516. Full text in Research Archive Show summary

  A high residential altitude impacts on the growth of children, and it has been suggested that linear growth (height) is more affected than body mass. The aim of the present study was to estimate the prevalence of obesity, overweight, underweight, and stunting in groups of native Tibetan children living at different residential altitudes (3700 vs 4300 m above sea level) and across ancestry (native Tibetan vs Han Chinese children living at the same altitude of 3700 m), as well as to examine the total effect of residential altitude and ancestry with stunting. Two cross-sectional studies of 1207 school children aged 9 to 10 years were conducted in Lhasa in 2005 and Tingri in 2007. Conventional age- and sex-specific cutoff values were used for defining underweight, normal weight, overweight, or obesity, whereas stunting was defined from sex-specific height-for-age z-scores (≤−2.0). The prevalence of underweight was high at 36.7% among Tingri Tibetan girls and 31.1% in Tingri Tibetan boys. The prevalence was statistically significant lower in Lhasa Tibetan girls (20.2%) than in both Tingri Tibetan girls and Han Chinese girls (33.7%), with a similar trend seen among boys. Severe and moderate stunting were found in 14.6% and 35.7%, respectively, of Tingri children, and near null among Han Chinese and native Tibetans in Lhasa. In logistic regression analyses, socioeconomic status and diet did not substantially change the observed crude association (total effect) (odds ratio [OR] = 3.3; 95% confidence interval [CI] 1.1–10.3) between ancestry and stunting. Similarly, adjustment for diet did not alter the crude association (direct effect) (OR = 101.3; 95% CI 37.1–276.4) between residential altitude and stunting. The prevalence estimates of stunting and underweight were high, and clearly higher among native Tibetan children living at a higher residential altitude (Tingri) than the lower residential altitude (Lhasa), in addition to being higher among Han Chinese children than Tibetan children living at the same residential altitude (Lhasa). Thus, physical growth according to age, in terms of both height and weight, affected children living at an altitude of 4300 m above sea level.

• Beelen, Rob; Hoek, Gerard; Raaschou-Nielsen, Ole; Stafoggia, Massimo; Andersen, Zorana Jovanovic & Weinmayr, Gudrun [Show all 72 contributors for this article] (2015). Natural-cause mortality and long-term exposure to particle components: An Analysis of 19 European cohorts within the multi-center ESCAPE project. Environmental Health Perspectives. ISSN 0091-6765. 123(6), p. 525–533. doi: 10.1289/ehp.1408095. Full text in Research Archive
• Magnus, Maria Christine; Stigum, Hein; Håberg, Siri Eldevik; Nafstad, Per; London, Stephanie J. & Nystad, Wenche (2015). Peak weight an heavy velocity to age 36 months and asthma development: the Norwegian Mother and Child Cohort Study. PLOS ONE. 10:e0116362(1), p. 1–13. doi: 10.1371/journal.pone.0116362. Full text in Research Archive Show summary

  Background The immediate postnatal period is the period of the fastest growth in the entire life span and a critical period for lung development. Therefore, it is interesting to examine the association between growth during this period and childhood respiratory disorders. Methods We examined the association of peak weight and height velocity to age 36 months with maternal report of current asthma at 36 months (n = 50,311), recurrent lower respiratory tract infections (LRTIs) by 36 months (n = 47,905) and current asthma at 7 years (n = 24,827) in the Norwegian Mother and Child Cohort Study. Peak weight and height velocity was calculated using the Reed1 model through multilevel mixed-effects linear regression. Multivariable log-binomial regression was used to calculate adjusted relative risks (adj.RR) and 95% confidence intervals (CI). We also conducted a sibling pair analysis using conditional logistic regression. Results Peak weight velocity was positively associated with current asthma at 36 months [adj.RR 1.22 (95%CI: 1.18, 1.26) per standard deviation (SD) increase], recurrent LRTIs by 36 months [adj.RR 1.14 (1.10, 1.19) per SD increase] and current asthma at 7 years [adj.RR 1.13 (95%CI: 1.07, 1.19) per SD increase]. Peak height velocity was not associated with any of the respiratory disorders. The positive association of peak weight velocity and asthma at 36 months remained in the sibling pair analysis. Conclusions Higher peak weight velocity, achieved during the immediate postnatal period, increased the risk of respiratory disorders. This might be explained by an influence on neonatal lung development, shared genetic/epigenetic mechanisms and/or environmental factors.

• Langballe, Ellen Melbye; Ask, Helga; Holmen, Jostein; Stordal, Eystein; Saltvedt, Ingvild & Selbæk, Geir [Show all 10 contributors for this article] (2015). Alcohol consumption and risk of dementia up to 27 years later in a large, population-based sample: the HUNT study, Norway. European Journal of Epidemiology (EJE). ISSN 0393-2990. 30(9), p. 1049–1056. doi: 10.1007/s10654-015-0029-2. Full text in Research Archive Show summary

  The relationship between alcohol consumption and dementia risk is unclear. This investigation estimates the association between alcohol consumption reported in a population-based study in the mid-1980s and the risk for dementia up to 27 years later. The entire adult population in one Norwegian county was invited to the Nord-Trøndelag Health Study during 1984–1986 (HUNT1): 88 % participated. The sample used in this study includes HUNT1 participants born between 1905 and 1946 who completed the questionnaire assessing alcohol consumption. A total of 40,435 individuals, of whom 1084 have developed dementia, are included in the analysis adjusted for age, sex, years of education, hypertension, obesity, smoking, and symptoms of depression. When adjusting for age and sex, and compared to reporting consumption of alcohol 1–4 times during the last 14 days (drinking infrequently), both abstaining from alcohol and reporting consumption of alcohol five or more times (drinking frequently) were statistically significantly associated with increased dementia risk with hazard ratios of 1.30 (95 % CI 1.05–1.61) and 1.45 (1.11–1.90), respectively. In the fully adjusted analysis, drinking alcohol frequently was still significantly associated with increased dementia risk with a hazard ratio of 1.40 (1.07–1.84). However, the association between dementia and abstaining from alcohol was no longer significant (1.15, 0.92–1.43). Equivalent results for Alzheimer’s disease and vascular dementia indicated the same patterns of associations. When adjusting for other factors associated with dementia, frequent alcohol drinking, but not abstaining from alcohol, is associated with increased dementia risk compared to drinking alcohol infrequently.

• Wang, M; Beelen, R; Bellander, T; Birk, M; Cesaroni, G & Cirach, M [Show all 41 contributors for this article] (2014). Performance of multi-city land use regression models for nitrogen dioxide and fine particles. Environmental Health Perspectives. ISSN 0091-6765. 122(8), p. 843–849. doi: 10.1289/ehp.1307271. Full text in Research Archive
• Bianba, X; Berntsen, Sveinung; Andersen, Lars Bo; Stigum, Hein; Ouzhuluobu, O. & Nafstad, Per [Show all 8 contributors for this article] (2014). Exercise capacity and selected physiological factors by ancestry and residential altitude: Cross-sectional studies of 9-10-year-old children in Tibet. High Altitude Medicine & Biology. ISSN 1527-0297. 15(2), p. 162–169. doi: 10.1089/ham.2013.1084. Full text in Research Archive
• Beelen, R; Stafogguiia, M; Raaschou-Nielsen, O; Andersen, ZJ; Xun, WW & Katsouyanni, K [Show all 74 contributors for this article] (2014). Long-term exposure to air pollution and cardiovascular mortality: An analysis of 22 European cohorts. Epidemiology. ISSN 1044-3983. 25(3), p. 368–378. doi: 10.1097/EDE.0000000000000076. Full text in Research Archive
• Strand, Bjørn Heine; Langballe, Ellen Melbye; Rosness, Tor Atle; Bergem, Astrid Liv Mina; Engedal, Knut Arne & Nafstad, Per [Show all 10 contributors for this article] (2014). Age, education and dementia related deaths. The Norwegian Counties Study and The Cohort of Norway. Journal of the Neurological Sciences. ISSN 0022-510X. 345(1-2), p. 75–82. doi: 10.1016/j.jns.2014.07.009. Full text in Research Archive
• Magnus, Maria Christine; deRoo, Lisa; Magnus, Per; Nafstad, Per; Nystad, Wenche & London, Stephanie J (2014). Prospective Study of Maternal Alcohol Intake During Pregnancy or Lactation and Risk of Childhood Asthma: The Norwegian Mother and Child Cohort Study. Alcoholism: Clinical and Experimental Research. ISSN 0145-6008. 38(4), p. 1002–1011. doi: 10.1111/acer.12348. Full text in Research Archive
• Dimakopoulou, K; Samoli, E; Beelen, R; Stafoggia, M; Andersen, ZJ & Hoffmann, B [Show all 59 contributors for this article] (2014). Air pollution and nonmalignant respiratory mortality in 16 cohorts within the ESCAPE project. American Journal of Respiratory and Critical Care Medicine. ISSN 1073-449X. 189(6), p. 684–696. doi: 10.1164/rccm.201310-1777OC. Full text in Research Archive
• Beelen, Rob; Raaschou-Nielsen, Ole; Stafoggia, Massimo; Andersen, Zorana Jovanovic; Weinmayr, Gudrun & Hoffmann, Barbara [Show all 76 contributors for this article] (2014). Effects of long-term exposure to air pollution on natural-cause mortality: An analysis of 22 European cohorts within the multicentre ESCAPE project. The Lancet. ISSN 0140-6736. 383(9919), p. 785–795. doi: 10.1016/S0140-6736(13)62158-3. Full text in Research Archive
• Sherpa, Lhamo Yangchen; Deji, -; Stigum, Hein; Chongsuvivatwong, Virasakdi; Nafstad, Per & Bjertness, Espen (2013). Prevalence of Metabolic Syndrome and Common Metabolic Components in High Altitude Farmers and Herdsmen at 3700 m in Tibet. High Altitude Medicine & Biology. ISSN 1527-0297. 14(1), p. 37–44. doi: 10.1089/ham.2012.1051. 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
• Raaschou-Nielsen, Ole; Andersen, Zorana J; Beelen, Rob; Samoli, Evangelia; Stafoggia, Massimo & Weinmayr, Gudrun [Show all 59 contributors for this article] (2013). Air pollution and lung cancer incidence in 17 European cohorts: prospective analyses from the European Study of Cohorts for Air Pollution Effects (ESCAPE). The Lancet Oncology. ISSN 1470-2045. 14(9), p. 813–822. doi: 10.1016/S1470-2045(13)70279-1. Full text in Research Archive
• Magnus, Maria Christine; Stene, Lars Christian; Håberg, Siri Eldevik; Nafstad, Per; Stigum, Hein & London, Stephanie J [Show all 7 contributors for this article] (2013). Prospective study of maternal mid-pregnancy 25-hydroxyvitamin D level and early childhood respiratory disorders. Paediatric and Perinatal Epidemiology. ISSN 0269-5022. 27(6), p. 532–541. doi: 10.1111/ppe.12080. Full text in Research Archive
• Zong, Yang; Berntsen, Sveinung; Bjertness, Espen; Stigum, Hein; Gonggalanzi, X & Bianba, X [Show all 7 contributors for this article] (2013). Lung Function Among 9-to 10-Year-Old Tibetan and Han Chinese Schoolchildren Living at Different Altitudes in Tibet. High Altitude Medicine & Biology. ISSN 1527-0297. 14(1), p. 31–36. doi: 10.1089/ham.2012.1034. Full text in Research Archive
• Håberg, Siri Eldevik; Trogstad, Lill; Gunnes, Nina; Wilcox, AJ; Gjessing, Håkon K. & Samuelsen, Sven Ove [Show all 19 contributors for this article] (2013). Risk of Fetal Death after Pandemic Influenza Virus Infection or Vaccination. New England Journal of Medicine. ISSN 0028-4793. 368(4), p. 333–340. doi: 10.1056/NEJMoa1207210. Full text in Research Archive
• Magnus, Maria Christine; VESTRHEIM, DIDRIK FRIMANN; Nystad, Wenche; Håberg, Siri Eldevik; Stigum, Hein & London, Stephanie J. [Show all 10 contributors for this article] (2012). Decline in early childhood respiratory tract infections in the Norwegian Mother and Child Cohort Study after introduction of pneumococcal conjugate vaccination. The Pediatric Infectious Disease Journal. ISSN 0891-3668. 31(9), p. 951–955. doi: 10.1097/INF.0b013e31825d2f76. Full text in Research Archive
• Madsen, Christian; Rosland, Pål; Hoff, Dominic Anthony; Nystad, Wenche; Nafstad, Per & Næss, Øyvind (2012). The short-term effect of 24-h average and peak air pollution on mortality in Oslo, Norway. European Journal of Epidemiology (EJE). ISSN 0393-2990. 27(9), p. 717–727. doi: 10.1007/s10654-012-9719-1. Full text in Research Archive
• Karlstad, Øystein; Nafstad, Per; Tverdal, Aage; Skurtveit, Svetlana & Furu, Kari (2012). Comorbidities in an asthma population 8-29 years old: a study from the Norwegian Prescription Database. Pharmacoepidemiology and Drug Safety. ISSN 1053-8569. 21(10), p. 1045–1052. doi: 10.1002/pds.2233. Full text in Research Archive Show summary

  Purpose: To examine occurrence of chronic diseases and antimicrobial treatment in an asthma population 8-29 years old, compared to the general population. Methods: In this cross-sectional study, the asthma population was identified from the general population (retrieved from a census covering the entire Norwegian population) by using filled prescriptions on asthma drugs as a proxy measure of current asthma. The outcome was excess occurrence of specific diseases (comorbidity) among asthmatics, compared to the age-specific general population. Diseases were defined by filled prescriptions with specific diagnostic codes with asthma, compared with the age-specific general population. Diseases were defined by filled prescriptions with specific diagnostic codes (International Classification of Primary Care 2nd edition [ICPC-2] or International Classification of Diseases 10th revision [ICD-10]) during a 1-year period in the Norwegian Prescription Database. Nine chronic diseases were examined: ADHD, epilepsy, migraine, mental illness, cardiovascular disease, diabetes, autoimmune disorders, gastro-oesophageal reflux disease (GORD), allergy. Additionally, antibacterials recommended for respiratory tract infections and antivirals were examined (defined by ATC codes). Standardized Morbidity Ratios (SMR) for each disease was calculated. Results: 59% of the population had at least one of nine chronic diseases examined, compared to 18% in the general population. Few individuals had more than one additional chronic disease (6% of males, 8% of females). SMRs were increased for all diseases except diabetes, implying higher than expected occurrence of the specific diseases in asthmatics. This pattern was observed in both age groups (8-19 and 20-29 years) and genders. Allergy and GORD had highest SMR (range 3.2-4.8) while the other diseases were in the range 1.2-2.5. Conclusions: An excess occurrence of comorbidities was found in the population with asthma. A majority of asthmatics had one additional chronic disease, and few had more than one.

• Yangzong, Yangzong; Shi, ZM; Nafstad, Per; Håheim, Lise Lund; Luobu, OZ & Bjertness, Espen (2012). The prevalence of childhood asthma in China: a systematic review. BMC Public Health. 12. doi: 10.1186/1471-2458-12-860. Full text in Research Archive Show summary

  Background It is well known that the prevalence of asthma has been reported to increase in many places around the world during the last decades. Therefore, the aim of this study was to identify and review studies of asthma prevalence among children in China and address time trends and regional variation in asthma. Methods A systematic literature search was performed using PubMed and China National Knowledge Infrastructure (CNKI) databases. Selected articles had to describe an original study that showed the prevalence of asthma among children aged 0−14 years. Results A total of 74 articles met the inclusion criteria. The lifetime prevalence of asthma varied between 1.1% in Lhasa (Tibet) and 11.0% in Hong Kong in studies following the International Study of Asthma and Allergies in Childhood (ISAAC) protocol. The prevalence was 3% or lower in most articles following Chinese diagnostic criteria. One article reported the results from two national surveys and showed that the current average prevalence of asthma for the total study population had increased from 1990 to 2000 (0.9% to 1.5%). The lowest current prevalence was found in Lhasa (0.1% in 1990, 0.5% in 2000). Conclusions The prevalence of childhood asthma was generally low, both in studies following the ISAAC and Chinese diagnostic criteria. Assessment of time trends and regional variations in asthma prevalence was difficult due to insufficient data, variation in diagnostic criteria, difference in data collection methods, and uncertainty in prevalence measures. However, the findings from one large study of children from 27 different cities support an increase in current prevalence of childhood asthma from 1990 to 2000. The lowest current prevalence of childhood asthma was found in Tibet.

• Karlstad, Øystein; Tverdal, Aage; Skurtveit, Svetlana; Nafstad, Per & Furu, Kari (2011). A prospective study of asthma and subsequent use of hypnotics in young adults. Pharmacoepidemiology and Drug Safety. ISSN 1053-8569. 20(4), p. 370–377. doi: 10.1002/pds.2101. Full text in Research Archive
• Sherpa, Lhamo Yangchen; Deji, -; Stigum, Hein; Chongsuvivatwong, Virasakdi; Luobu, Ouzhu & Thelle, Dag Steinar [Show all 8 contributors for this article] (2011). Lipid Profile and Its Association with Risk Factors for Coronary Heart Disease in the Highlanders of Lhasa, Tibet. High Altitude Medicine & Biology. ISSN 1527-0297. 12(1), p. 57–63. doi: 10.1089/ham.2010.1050. Full text in Research Archive
• Polańska, Kinga; Hanke, Wojciech; Jurewicz, Joanna; Sobala, Wojciech; Madsen, Christian & Nafstad, Per [Show all 7 contributors for this article] (2011). Polish mother and child cohort study (REPRO_PL) - Methodology of follow-up of the children. International Journal of Occupational Medicine and Environmental Health. ISSN 1232-1087. 24(4), p. 391–398. doi: 10.2478/s13382-011-0026-y. Full text in Research Archive
• Madsen, Christian; Gehring, Ulrike; Håberg, Siri Eldevik; Nafstad, Per; Meliefste, Kees & Nystad, Wenche [Show all 8 contributors for this article] (2011). Comparison of land-use regression models for predicting spatial NOx contrasts over a three year period in Oslo, Norway. Atmospheric Environment. ISSN 1352-2310. 45(21), p. 3576–3583. doi: 10.1016/j.atmosenv.2011.03.069. Full text in Research Archive
• Magnus, Maria Christine; Håberg, Siri Eldevik; Stigum, Hein; Nafstad, Per; London, SJ & Vangen, Siri [Show all 7 contributors for this article] (2011). Delivery by cesarean section and early childhood respiratory symptoms and disorders the Norwegian Mother and Child Cohort Study. American Journal of Epidemiology. ISSN 0002-9262. 174(11), p. 1275–1285. doi: 10.1093/aje/kwr242. Full text in Research Archive
• Hancock, Dana B; Håberg, Siri Eldevik; Furu, Kari; Whitworth, Kristina W; Nafstad, Per & Nystad, Wenche [Show all 7 contributors for this article] (2011). Oral contraceptive pill use before pregnancy and respiratory outcomes in early childhood. Pediatric Allergy and Immunology. ISSN 0905-6157. 22(5), p. 528–536. doi: 10.1111/j.1399-3038.2010.01135.x. Full text in Research Archive
• Furu, Kari; Karlstad, Øystein; Skurtveit, Svetlana; Håberg, Siri Eldevik; Nafstad, Per & London, Stephanie J [Show all 7 contributors for this article] (2011). High validity of mother-reported use of antiasthmatics among children: a comparison with a population-based prescription database. Journal of Clinical Epidemiology. ISSN 0895-4356. 64(8), p. 878–884. doi: 10.1016/j.jclinepi.2010.10.014. Full text in Research Archive
• Bentdal, Yngvild E; Håberg, Siri Eldevik; Karevold, Gunnhild; Stigum, Hein; Kværner, Kari J & Nafstad, Per (2010). Birth characteristics and acute otitis media in early life. International Journal of Pediatric Otorhinolaryngology. ISSN 0165-5876. 74(2), p. 168–172. doi: 10.1016/j.ijporl.2009.11.001. Full text in Research Archive
• Håberg, Siri Eldevik; Bentdal, YE; London, SJ; Kværner, KJ; Nystad, Wenche & Nafstad, Per (2010). Prenatal and postnatal parental smoking and acute otitis media in early childhood. Acta Paediatrica. ISSN 0803-5253. 99(1), p. 99–105. doi: 10.1111/j.1651-2227.2009.01506.x. Full text in Research Archive
• Madsen, Christian; Gehring, Ulrike; Walker, Sam-Erik; Brunekreef, Bert; Stigum, Hein & Næss, Øyvind Erik [Show all 7 contributors for this article] (2010). Ambient air pollution exposure, residential mobility and term birth weight in Oslo, Norway. Environmental Research. ISSN 0013-9351. 110(4), p. 363–371. doi: 10.1016/j.envres.2010.02.005. Full text in Research Archive
• Karlstad, Øystein; Nafstad, Per; Tverdal, Aage; Skurtveit, Svetlana & Furu, Kari (2010). Prevalence, incidence and persistence of anti-asthma medication use in 2-to 29-year-olds: a nationwide prescription study. European Journal of Clinical Pharmacology. ISSN 0031-6970. 66(4), p. 399–406. doi: 10.1007/s00228-009-0749-x. Full text in Research Archive
• Håberg, Siri Eldevik; Stigum, Hein; London, Stephanie J; Nystad, Wenche & Nafstad, Per (2009). Maternal obesity in pregnancy and respiratory health in early childhood. Paediatric and Perinatal Epidemiology. ISSN 0269-5022. 23(4), p. 352–362. doi: 10.1111/j.1365-3016.2009.01034.x. Full text in Research Archive
• Håheim, Lise Lund; Nafstad, P; Olsen, Ingar; Schwarze, PE & Rønningen, Kjersti Skjold (2009). C-reactive protein variations for different chronic somatic disorders. Scandinavian Journal of Public Health. ISSN 1403-4948. 37(6), p. 640–646. doi: 10.1177/1403494809104358. Full text in Research Archive
• Oftedal, Bente Margaret; Nystad, Wenche; Brunekreef, Bert & Nafstad, Per (2009). Long-term traffic-related exposures and asthma onset in schoolchildren in Oslo, Norway. Environmental Health Perspectives. ISSN 0091-6765. 117(5), p. 839–844. doi: 10.1289/ehp.11491. Full text in Research Archive
• Håberg, Siri Eldevik; London, SJ; Stigum, Hein; Nafstad, Per & Nystad, Wenche (2009). Folic acid supplements in pregnancy and early childhood respiratory health. Archives of Disease in Childhood. ISSN 0003-9888. 94(3), p. 180–184. doi: 10.1136/adc.2008.142448. Full text in Research Archive
• Oftedal, Bente Margaret; Walker, Sam-Erik; Gram, Frederick; McInnes, Harold & Nafstad, Per (2009). Modelling long-term averages of local ambient air pollution in Oslo, Norway: evaluation of nitrogen dioxide, PM10 and PM2.5. International Journal of Environment and Pollution. ISSN 0957-4352. 36(1-3), p. 110–126. Full text in Research Archive
• Karevold, Gunnhild; Bentdal, Yngvild E; Nafstad, Per & Kvaerner, Kari Jorunn (2009). Surgery for otitis media and infectious susceptibility in 10-year old school children. International Journal of Pediatric Otorhinolaryngology. ISSN 0165-5876. 73(4), p. 603–606. doi: 10.1016/j.ijporl.2008.12.007. Full text in Research Archive
• Nystad, Wenche; Haberg, SE; Håberg, Siri Eldevik; London, Stephanie J; Nafstad, Per & Magnus, Per (2008). Baby swimming and respiratory health. Acta Paediatrica. ISSN 0803-5253. 97(5), p. 657–662. doi: 10.1111/j.1651-2227.2008.00756.x. Full text in Research Archive

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• Parr, Christine Louise; Nystad, Wenche; Karlstad, Øystein; Øymar, Knut Asbjørn Alexander; Langhammer, Arnulf & Nafstad, Per [Show all 7 contributors for this article] (2022). Ten-year trends of national healthcare costs of asthma, allergic rhinitis, and atopic eczema in 3 million Norwegians. Allergy. European Journal of Allergy and Clinical Immunology. ISSN 0105-4538. doi: 10.1111/all.15225. Full text in Research Archive
• Bernhoft, Aksel; Aamodt, Geir; Nafstad, Per; Skalleberg, Katrine; Nordh, Helena & Butenschøn, Peter [Show all 12 contributors for this article] (2018). Grønn helse i byen - hva betyr grønne omgivelser og matproduksjon i byer for vår helse? In Videnskaps-Akademi, Det Norske Videnskaps-Akademi Det Norske (Eds.), Årbok 2017. Novus Forlag. ISSN 9788270999149. p. 319–333. Full text in Research Archive
• Håheim, Lise Lund; Nafstad, Per; Schwarze, Per Everhard; Olsen, Ingar; Rønningen, Kjersti Skjold & Thelle, Dag Steinar (2018). Predictors of stroke mortality. A comparison of the Oslo-study 1972/73 and the Oslo II-study in 2000. Full text in Research Archive
• Gonggalanzi, X & Nafstad, Per (2017). Response to letter to the editor regarding "Acute mountain sickness among tourists visiting the high-altitude city of Lhasa, Tibet, China at 3658 m above sea level: A cross-sectional study". Archives of Public Health. ISSN 0778-7367. 75(20). doi: 10.1186/s13690-017-0188-6. Full text in Research Archive
• Parr, Christine Louise; Page, Christian; Holvik, Kristin; Sandanger, Torkjel M; Nøst, Therese Haugdahl & Magnus, Maria Christine [Show all 13 contributors for this article] (2017). Pregnancy fatty acid status and newborn DNA methylation: the MoBa pregnancy cohort. Full text in Research Archive
• Håberg, Siri Eldevik; Trogstad, Lill; Gunnes, Nina; Wilcox, Allen J; Gjessing, Håkon K. & Samuelsen, Sven Ove [Show all 19 contributors for this article] (2013). Risk of Fetal Death After Pandemic Influenza Virus Infection or Vaccination EDITORIAL COMMENT. Obstetrical and Gynecological Survey. ISSN 0029-7828. 68(5), p. 348–349. doi: 10.1097/01.ogx.0000430377.29993.2b. Full text in Research Archive
• Magnus, Maria Christine; Nafstad, Per; Stene, Lars Christian; Håberg, Siri Eldevik; London, Stephanie J. & Stigum, Hein [Show all 7 contributors for this article] (2013). Maternal Vitamin D Status During Pregnancy and Asthma in the Offspring Among Participants in the Norwegian Mother and Child Cohort Study. Journal of Allergy and Clinical Immunology. ISSN 0091-6749. 131(2), p. AB128–AB128. Full text in Research Archive
• Håberg, Siri Eldevik; Trogstad, Lill; Gunnes, Nina; Gjessing, Håkon K.; Samuelsen, Sven Ove & Cappelen, Inger [Show all 17 contributors for this article] (2012). The 2009 Influenza Pandemic, Vaccination during Pregnancy and Fetal Death: A National Registry-Based Study in Norway. Pharmacoepidemiology and Drug Safety. ISSN 1053-8569. 21, p. 382–382. Full text in Research Archive
• Hancock, DB; Håberg, Siri Eldevik; Furu, Kari; Whitworth, Kristina W; Nafstad, Per & Nystad, Wenche [Show all 7 contributors for this article] (2011). Oral contraceptive use before pregnancy and respiratory outcomes in the offspring: comparison of Estrogen-Progestin combined pills and Progestin-Only pills. Journal of Allergy and Clinical Immunology. ISSN 0091-6749. 127(2), p. AB173–AB173. Full text in Research Archive
• Oftedal, Bente Margaret; Panasevich, Sviatlana; Nafstad, Per; Schwarze, Per E & Aasvang, Gunn Marit (2011). Road traffic noise, air pollution and hypertension in a population-based sample in Oslo. Norsk Epidemiologi, Supplement. ISSN 0803-4206. 21, p. 36–36. Full text in Research Archive
• Håberg, Siri Eldevik; London, Stephanie J.; Nafstad, Per; Nilsen, Roy Miodini; Ueland, Per Magne & Vollset, Stein Emil [Show all 7 contributors for this article] (2011). Maternal folate levels in pregnancy and asthma in children at age 3 years. Journal of Allergy and Clinical Immunology. ISSN 0091-6749. 127(1), p. 262–264. doi: 10.1016/j.jaci.2010.10.004. Full text in Research Archive
• Håheim, Lise Lund; Nafstad, Per; Olsen, Ingar; Schwarze, Per & Rønningen, Kjersti Skjold (2010). C-reaktivt protein (CRP) varierer ved forskjellige kroniske lidelser. Den norske tannlegeforenings Tidende. ISSN 0029-2303. 120(1), p. 46–46. Full text in Research Archive
• Karlstad, Øystein; Tverdal, Aage; Skurtveit, Svetlana; Nafstad, Per & Furu, Kari (2010). A prospective study of self-reported asthma and subsequent use of hypnotics. Full text in Research Archive
• Håberg, Siri Eldevik; London, SJ; Ueland, Per Magne; Vollset, Stein Emil; Nilsen, Rune & Nafstad, Per [Show all 7 contributors for this article] (2010). Maternal Folate Levels in Pregnancy and Asthma at 3 Years of Age. Journal of Allergy and Clinical Immunology. ISSN 0091-6749. 125(2), p. AB128–AB128. Full text in Research Archive
• Karlstad, Øystein; Skurtveit, Svetlana; Nafstad, Per; Tverdal, Aage & Furu, Kari (2010). Comorbidities in the treated asthma population under 30 years of age- a prescription study from the Norwegian Prescription Database. Full text in Research Archive
• Karlstad, Øystein; Skurtveit, Svetlana; Tverdal, Aage; Nafstad, Per & Furu, Kari (2010). A prospective study of asthma and subsequent use of hypnotics. Pharmacoepidemiology and Drug Safety. ISSN 1053-8569. 19, p. s248–s248. doi: 10.1002/pds.2019. Full text in Research Archive
• Madsen, Christian; Gehring, U; Walker, SE; Brunekreef, B; Stigum, Hein & Næss, Øyvind Erik [Show all 7 contributors for this article] (2009). Ambient Air Pollution Exposure, Residential Mobility and Term Birth Weight in Oslo, Nonway. Epidemiology. ISSN 1044-3983. 20(6), p. S151–S151. Full text in Research Archive
• Oftedal, Bente Margaret; Aasvang, Gunn Marit; Biswas, Ruhina Tasmin; Watanabe, Sachiko; Nafstad, Per & Nystad, Wenche [Show all 7 contributors for this article] (2009). Long-term exposure to residential noise and air pollution and risk of cardiovascular diseases in Oslo, Norway- Project design and exposure assessment. Epidemiology. ISSN 1044-3983. 20(6), p. S204–S204. doi: 10.1097/01.ede.0000362685.98715.98. Full text in Research Archive
• Furu, Kari; Karlstad, Øystein; Skurtveit, Svetlana; Håberg, Siri Eldevik; Nafstad, Per & London, Stephanie [Show all 7 contributors for this article] (2009). The validity of mother-reported asthma and asthma medication use in children. Pharmacoepidemiology and Drug Safety. ISSN 1053-8569. 18, p. S104–S104. doi: 10.1002/pds. Full text in Research Archive
• Oftedal, Bente Margaret; Aasvang, Gunn Marit; Biswas, Ruhina Tasmin; Nafstad, Per; Nystad, Wenche & Schwarze, Per E (2009). Exposure to long-term traffic noise, noise annoyance and blood pressure. Norsk Epidemiologi. ISSN 0803-2491. 19, p. 51–51. Full text in Research Archive
• Biswas, Ruhina Tasmin; Oftedal, Bente Margaret; Aasvang, Gunn Marit; Schwarze, Per E; Nafstad, Per & Knardahl, Stein (2009). Noise-annoyance from traffic and plasma cortisol in a population based study. Norsk Epidemiologi. ISSN 0803-2491. 19, p. 49–49. Full text in Research Archive
• Karlstad, Øystein; Furu, Kari; Skurtveit, Svetlana; Håberg, Siri Eldevik; Nafstad, Per & London, Stephanie J [Show all 7 contributors for this article] (2009). The validity of mother-reported asthma and asthma medication use in 7 year old children. Full text in Research Archive
• Aarhus, Lisa; Engdahl, Bo Lars; Tambs, Kristian & Nafstad, Per (2016). Follow-up of childhood hearing disorders: hearing loss, tinnitus and dizziness in adulthood. Universitetet i Oslo. ISSN 9788283331455. Full text in Research Archive
• Løwer, Hege Line Magnussen; Aavitsland, Preben; Skjeldestad, Finn Egil & Nafstad, Per (2016). Data Quality in Norwegian Surgical Site Infection Surveillance. Implementation and validation of a national system for surveillance of surgical site infections in Norway. Universitetet i Oslo. Full text in Research Archive Show summary

  Surgical site infections (SSIs) constitute about one quarter of all healthcareassociated infections in Norway and are associated with a substantial cost for hospitals, patients and the community. Surveillance with feedback has been proven to be a useful tool in prevention of adverse events. In Norway, SSI surveillance was initiated through the establishment of the Norwegian Surveillance System for Antibiotic Consumption and Healthcare-Associated Infections (NOIS) by regulation in 2005. The overall aim of this thesis was to describe and validate NOIS-SSI in order to ensure good data quality through a uniform, robust and feasible system for monitoring and controlling SSIs. This was achieved through three sub-studies, each reported in a separate paper. The first study gives a description of the methodology of NOIS-SSI, and the value of a mandatory system with automated data collection and post-discharge surveillance. The second study is an investigation of the completeness, representativeness and accuracy of the denominator data by comparing NOIS-SSI to administrative data. The third study is an investigation of the necessity of post-discharge surveillance and the consequences of differing duration and intensity of follow-up of patients after hospital discharge. Paper I reports a steadily increasing participation in NOIS-SSI during 2005-2009, with many hospitals implementing computerized systems and submitting extra data voluntarily. We found reasonable quality of the risk-adjustment variables and a very good post-discharge follow-up, with 81% of SSIs being detected after hospital discharge. Paper II shows that the completeness of NOIS-SSI's denominator data improved greatly between 2005-2010 and that hospital participation became more representative over time. However, NOIS-SSI did not achieve representativeness for all surgical procedures. The hospitals which participated, submitted accurate denominator data and all the computerized systems delivered data of high quality. In paper III, we found that 82% of the deep SSIs after hip arthroplasty in 2005-2011 were detected after discharge from hospital. All of the patients with deep SSIs that were detected between 30 days and one year after hospital discharge were readmitted, which means that they could have been detected through the hospitals' computer systems instead of by patient questionnaire. A mandatory surveillance system should give more complete and unbiased data than a voluntary system. NOIS-SSI was not complete and representative and this was mostly due to a flexible and incremental implementation strategy. The upside of this flexibility was the establishment of electronically based surveillance systems in almost all hospitals. Electronically based systems have led to good quality of riskadjustment variables and excellent accuracy. Because most SSIs are detected after hospital discharge, active follow-up of the patient after discharge is important for correct case ascertainment. Active follow-up is resource demanding, but without it most SSIs would go undetected and the infection rates would be incorrect. Validation of correct classification of SSIs according to surveillance definitions has not been performed in Norway. Some studies have indicated good-to-excellent sensitivity and specificity in SSI validation by retrospective chart review, whereas others have found poor inter-rater agreement. Information technology in surveillance is in rapid development, and much has been published about computer algorithm-assisted case detection in existing clinical and administrative databases. Although there are many potential pitfalls in utilizing more automated surveillance, it is time and cost efficient and circumvents many of the issues associated with manual systems. All-year, all-procedure mandatory surveillance was implemented in Norway from 2012/2013. The findings of this thesis have led to changes in the Norwegian surveillance system, and one-year follow-of hip arthroplasty patients by letter will be replaced by surveillance through readmissions in 2015. By continually improving and upgrading the system we hope to achieve a surveillance system that is robust, efficient and useful. Acting on the basis of surveillance data in a clinical setting is the ultimate goal of a surveillance system. High quality data are essential in this process, and more use of automated case-finding may be an important asset in achieving this.

• Fleten, Anne Caroline; Nafstad, Per; Stigum, Hein; Brunborg, Gunnar; Schwarze, Per E & Aasvang, Gunn Marit [Show all 8 contributors for this article] (2009). Miljørettet helsevern : kjemiske, fysiske og biologiske miljøforholds betydning for helse i vårt land og fordelingen av disse. Nasjonalt folkehelseinstitutt. ISSN 9788280823267. Full text in Research Archive
• Madsen, Christian & Nafstad, Per (2009). Urban environmental exposures and potential markers of risk for cardiovascular disease. Unipub forlag. ISSN 9788280729675. Full text in Research Archive

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