Petter Laake

• Larsen, Bjørn Kjetil; Laake, Petter; Strype, Jon & Ødegård, Atle (2026). Validating the Perception of Sex Offenders Scale (PSO) Among Norwegian Students in Health, Social Work, and Police Education. BMC Measurement Instruments for the Social Sciences. 8(2026). doi: 10.5964/miss.19995. Fulltekst i vitenarkiv Vis sammendrag

  Reliable instruments are essential for studying perceptions of individuals convicted of sexual offences across cultural contexts. This study evaluates the psychometric properties of the Perceptions of Sex Offenders Scale (PSO) among Norwegian students in nursing, social education, social work, and police education (N = 282). Using confirmatory factor analysis, we tested the fit of the PSO’s original three-factor structure. The model showed mixed fit (RMSEA = .072; SRMR = .072; CFI = .86; TLI = .84). Internal consistency was satisfactory for Sentencing and Management and Stereotype Endorsement (α = .82 and .70), but low for Risk Perception (α = .53). Internal validity indices were uneven: composite reliability was acceptable for Sentencing and Management and Stereotype Endorsement (CR = .89 and .71), but not for Risk Perception (CR = .58), and AVE values were below recommended thresholds across factors, particularly for Risk Perception (AVE = .227). Free-text responses indicated that participants primarily had rape and child sexual abuse in mind when responding to the PSO. Overall, the PSO shows promise in a Norwegian student context, but the Risk Perception dimension appears to require refinement before the scale can be used confidently for research and educational purposes.

• Ødegård, Atle; Strype, Jon; Lindqvist, Susanne; Vasset, Frøydis Perny; Willumsen, Anna Elisabeth & Iversen, Hans Petter [Vis alle 8 forfattere av denne artikkelen] (2025). Teachers’ perceptions of interprofessional collaboration in higher education: Contributions to a framework. Social Sciences & Humanities Open (SSHO). 11. doi: 10.1016/j.ssaho.2025.101300. Fulltekst i vitenarkiv
• Otterholt, Eli; Laake, Petter; Bjørkly, Stål Kapstø & Andersson, Helle Wessel (2025). Salivary cortisol trajectories among inpatients undergoing substance use disorder treatment : a prospective repeated-measures study. Psychoneuroendocrinology. ISSN 0306-4530. 178(August), s. 1–8. doi: 10.1016/j.psyneuen.2025.107477. Fulltekst i vitenarkiv Vis sammendrag

  Background A growing body of research among inpatients with substance use disorders (SUD) suggests a link between cortisol levels and treatment outcomes. However, there is limited insight into the pattern of cortisol level during an inpatient SUD treatment stay. Aim The aim was to investigate changes in salivary cortisol levels during 8 weeks of an inpatient SUD treatment stay, and to determine whether the primary SUD diagnosis exerted a distinct effect on cortisol level trajectories. Methods We employed a prospective repeated-measures design and followed a cohort of patients with various SUD diagnoses. Salivary cortisol samples were collected at four time points during the first 8 weeks of the treatment stay (t1: week 2 (baseline); t2: week 4; t3: week 6; and t4: week 8). We assessed basal cortisol concentration by calculating the area under the curve with respect to ground (AUCG), which represents total daily cortisol output. Associations were determined using Linear mixed model analyses (LMMs). Results The analytic sample comprised 173 patients. The full LMM model, including covariates (i.e. polysubstance disorder, age, gender, treatment history, treatment unit, mental distress) revealed that cortisol levels decreased from t1 to t2 (β = –7.218; 95 % CI: –11.126 to −3.310; p < 0.001) and stabilized thereafter. Patients with opioid use disorders (OUD) had lower cortisol level trajectories than patients with stimulant use disorders (β=-20.357; 95 % CI: −29.394 to −11.319; p < 0.001), while patients treated in the long-term unit showed elevated cortisol trajectories relative to those in the short-term unit (β=6.650; 95 % CI: 0.072–13.229; p = 0.048). Conclusion This study showed a decline in cortisol levels during the first 4 weeks of SUD inpatient treatment, followed by stabilization. Patients with stimulant use disorders had higher cortisol levels over time than those with OUD. Further research should explore the clinical implications of the current findings. In particular, greater insight into the moderating effects of polysubstance disorders on cortisol levels may contribute to the development of individual tailored treatment approaches.

• Helgeland, Jon & Laake, Petter (2025). A mixture of mixed regressions model for longitudinal data, with application to clinical laboratory measurements. Communications in Statistics - Theory and Methods. ISSN 0361-0926. 54(22), s. 7158–7174. doi: 10.1080/03610926.2025.2467202. Fulltekst i vitenarkiv Vis sammendrag

  We study a statistical model for longitudinal data from a mixture of populations with different mean structures, with a view to analyzing clinical laboratory data. Different configurations of learning data are discussed, including the case where external summary statistics are known for one population. An EM algorithm is used for fitting the model. We discuss the asymptotic properties of the model, and show that there exists a consistent root of the likelihood equations with standard properties. A simulation study with linear and fractional polynomial models to study finite sample bias, variance, as well as parameter standard deviation estimators based on nonparametric bootstrapping and asymptotic distributions, is included. The separation between populations was the most important factor for estimator performance. Nonparametric bootstrapping performed reasonably well in general when separation was large, but was unsatisfactory in some cases with small separation. The asymptotic distributions were in general reasonable for large separation, but very inaccurate in other cases, and seem to be of limited practical value. We also present an example on measurements of cardiac enzymes for data sets comprising both healthy patients and patients with acute myocardial infarction.

• Brevik, Thea Beate; Laake, Petter; Bjørkly, Stål Kapstø; Leer-Salvesen, Kjartan & Vatnar, Solveig Karin Bø (2024). An educational intervention study on mandatory reporting of intimate partner violence: changes in knowledge and attitudes among healthcare providers. BMC Medical Education. 24(1). doi: 10.1186/s12909-024-06120-8. Fulltekst i vitenarkiv Vis sammendrag

  Background: Intimate partner violence (IPV) is a major public health concern. Healthcare providers can play a crucial role in reporting cases of IPV or suspected IPV injuries to the police or the criminal justice system, commonly referred to as mandatory reporting. However, mandatory reporting of intimate partner violence (MR-IPV) is a debated topic that can pose complex challenges for healthcare providers. This underscores the importance of training programs to ensure that healthcare providers can fulfill their MR-IPV obligations. Methods: We developed an educational intervention on MR-IPV and assessed its impact on healthcare providers’ knowledge and attitudes. The study used a pre- and post-test design with three measurement points: baseline (T0), immediately after the intervention (T1), and six months later (T2). The intervention was conducted at a university college in Norway, with data collected between October 2022 and May 2023. The intervention was delivered to 37 healthcare providers who were currently part-time students in mental healthcare. Changes in knowledge and attitudes between T0 and T1, and T0 and T2 were analyzed through nonparametric tests on related samples using the Marginal homogeneity (Stuart–Maxwell) test. Risk differences (RD), along with their corresponding 95% confidence intervals (CI), were calculated for selected categories. Results: The number of participants knowing the MR law increased from 2.9% at baseline to 62.9% at T1 (RD = 0.60, 95% CI: 0.41—0.79) and to 31.4% at T2 (RD = 0.29, 95% CI: 0.11–0.46). The number of participants reporting knowing relevant criteria increased from 0.0% at baseline to 68.6% at T1 (RD = 0.69, 95% CI: 0.50–0.87) and to 34.3% at T2 (RD = 0.34, 95% CI: 0.16—0.53). We observed several persistent changes in healthcare providers' attitudes towards MR, including finding MR to be a useful instrument and generally complying with MR requirements. Conclusions: The findings suggest that this educational intervention can have a positive impact on healthcare providers' attitudes and compliance with MR-IPV. Before the intervention, few participants reported knowing the MR law and its application criteria, demonstrating the importance of continuous learning and evidence-based training programs.

• Brevik, Thea Beate; Calegari, Lara Rodrigues da Matta; Metcalfe, Isabel Mosquera; Laake, Petter; Maza, Mauricio & Basu, Partha [Vis alle 8 forfattere av denne artikkelen] (2023). Training health care providers to administer VIA as a screening test for cervical cancer : a systematic review of essential training components. BMC Medical Education. 23, s. 1–11. doi: 10.1186/s12909-023-04711-5. Fulltekst i vitenarkiv Vis sammendrag

  Background: Training health care providers to administer visual inspection after application of acetic acid (VIA) is paramount in improving cervical cancer screening services for women in low- and middle-income countries. The objective of this systematic review was to create a framework of essential VIA training components and provide illustrating examples of how VIA training programs can be carried out in different clinical settings. Methods: A systematic review of PubMed, Embase, and Web of Science (from 2006 to 2021) was undertaken. Our inclusion criteria comprised articles reporting on implemented cervical cancer screening programs using VIA in a screen-and-treat approach. Trained health care providers with any level of health education were included, and the outcome of interest was the reporting of training components. Data were extracted by two reviewers, and a narrative synthesis of the training programs was performed. We developed a framework of seven essential training components and applied it to assess how training courses were conducted in different settings. Results: 13 primary studies were eligible for inclusion, including 2,722 trained health care providers and 342,889 screened women. Most training courses lasted 5–7 days and included theoretical education, practical skill development, and competence assessment. It was unclear how visual aids and training in client counselling and quality assessment were integrated in the training courses. After the training course, nearly all the VIA training programs made provisions for on-job training at the providers’ own clinical settings through supervision, feedback, and refresher training. Conclusions: This study demonstrates the feasibility of implementing international training recommendations for cervical cancer screening in real-world settings and provides valuable examples of training program implementation across various clinical settings. The diverse reporting practices of quality indicators in different studies hinder the establishment of direct links between these data and training program effectiveness. To enhance future reporting, authors should emphasize specific training components, delivery methods, and contextual factors. Standardized reporting of quality indicators for effective evaluation of VIA training programs is recommended, fostering comparability, facilitating research, and enhancing reporting quality in this field.

• Mundal, Ingunn Pernille; Laake, Petter; Bjørkly, Stål & Cabrera, Mariela Loreto Lara (2023). Factor structure and internal consistency of the parent patient activation measure (P-PAM) in parents of children with ADHD in norwegian paediatric mental health. BMC Psychiatry. 23(1). doi: 10.1186/s12888-023-04550-0. Fulltekst i vitenarkiv Vis sammendrag

  Background: This study aimed to explore the internal consistency and factor validity of the 13-item self-report questionnaire Parent-Patient Activation Measure (P-PAM) in a sample of parents of children with Attention-deficit/hyperactivity disorder. Methods: In a cross-sectional study, 239 parents were recruited from four outpatient clinics of the Child and Adolescent Mental Health Services and completed the P-PAM along with demographic variables. The factor structure of the P-PAM was examined through exploratory factor analysis, and internal consistency was estimated with the use of both Cronbach’s alpha and McDonald’s omega. A confirmatory factor analysis was used to estimate and test individual parameters. Results: The fit indices suggest an acceptable two-factor model of P-PAM and show high internal consistency and reliability for both factors, indicating that the scale measures two concepts. Conclusions: Our findings provide evidence for an acceptable factor structure and a high reliability of P-PAM as a measure of parent activation, suggesting that the theoretical factors reflect the construct of parent activation as intuitively compiled into an inner cognitive factor and an outer behavioral factor, which are related.

• Løvgren, Pia Jorde; Laake, Petter; Narud, Kjersti; Reitan, Solveig Klæbo & Bjørkly, Stål Kapstø (2023). Are symptoms assessed differently for schizophrenia and other psychoses in legal insanity evaluations of violent crimes? BMC Psychiatry. 23(1), s. 1–14. doi: 10.1186/s12888-023-04992-6. Fulltekst i vitenarkiv Vis sammendrag

  Background: Forensic evaluations of legal insanity include the experts’ assessment of symptoms present at the mental state examination (MSE) and the mental state at the time of offense (MSO). Delusions and hallucinations are most important. We explored how often symptoms were recorded in written forensic reports. Design: This exploratory, cross-sectional study included 500 reports of legal insanity written in 2009–2018 from cases of violent crimes in Norway. The first author read all reports and coded symptoms recorded from the experts’ assessments of the offenders. Two co-authors repeated this procedure for 50 randomly selected reports. Interrater reliability was calculated with Gwet’s AC1. Generalized Linear Mixed Models with Wald tests for fixed effects and Risk Ratios as effect sizes were used for the statistical analyses. Results: Legal insanity was the main conclusion in 23.6% of the reports; 71.2% of these were diagnosed with schizophrenia while 22.9% had other psychotic disorders. Experts recorded few symptoms from MSO, but more from MSE, although MSO is important for insanity. We found a significant association between delusions and hallucinations recorded present in the MSO and legal insanity for defendants with other psychotic disorders, but no association for defendants with schizophrenia. The differences in symptom recordings between diagnoses were significant. Conclusion: Few symptoms were recorded from the MSO. We found no association between presence of delusions or hallucinations and legal insanity for defendants with schizophrenia. This may indicate that a schizophrenia diagnosis is more important to the forensic conclusion than the symptoms recorded in the MSO. Keywords: delusions, hallucinations, forensic, insanity, bias, stigma

• Løvgren, Pia Jorde; Laake, Petter; Reitan, Solveig Merete Klæbo & Narud, Kjersti (2022). Use of assessment instruments in forensic evaluations of criminal responsibility in Norway. BMC Psychiatry. 22(1), s. 1–14. doi: 10.1186/s12888-022-03831-4. Fulltekst i vitenarkiv Vis sammendrag

  Objectives Assessment instruments are often used to enhance quality and objectivity in therapeutic and legal settings. We aimed to explore the use of instruments in Norwegian reports of forensic evaluations of criminal responsibility; specifically, whether this use was associated with diagnostic and forensic conclusions. Methods Our study has an exploratory cross-sectional design. We examined 500 reports filed with the Norwegian Board of Forensic Medicine in 2009–2018 regarding defendants indicted for the most serious violent crimes. The first author coded data from all reports according to a registration form developed for this study. Two co-authors then coded a random sample of 50 reports, and inter-rater reliability measures were calculated. The first author coded 41 reports for calculation of intra-rater reliability. Descriptive statistics are presented for the use of assessment instruments, and a generalized linear mixed model (GLMM) was used to estimate associations between the use of instruments and diagnostic and forensic conclusions. Results Instruments were used in 50.0% of reports. The Wechler’s Adult Intelligence Scale (WAIS), Historical Clinical Risk-20 (HCR-20), and the Structured Clinical Interview for DSM disorders (SCID I), were used in 15.8, 13.8, and 9.0% of reports, respectively. The use of instruments increased from 36% in 2009 to 58% in 2015; then decreased to 49% in 2018. Teams of two experts wrote 98.0% of reports, and 43.4% of these teams comprised two psychiatrists. In 20.0% of reports, the diagnostic conclusion was schizophrenia, and in 8.8% it was other psychotic disorders. A conclusion of criminal irresponsibility was given in 25.8% of reports. Instruments were more often used in reports written by teams that comprised both a psychiatrist and a psychologist, compared to reports by two psychiatrists. The use of instruments was strongly associated with both diagnostic and forensic conclusions. Conclusion Instruments were used in 50% of reports on forensic evaluations of criminal responsibility in Norway, and their use increased during the study period. Use of instruments was associated with diagnostic and forensic conclusions.

• Bjørkly, Stål; Laake, Petter & Douglas, Kevin Stewart (2022). The safe pilot study : a prospective naturalistic study with repeated measures design to test protective factors against violence in and after discharge from forensic facilities. Psychiatry Research. ISSN 0165-1781. 320(February), s. 1–8. doi: 10.1016/j.psychres.2022.115017. Fulltekst i vitenarkiv Vis sammendrag

  Assessing violence risk amongst forensic patients is a vital legal and clinical task. The field of violence risk assessment has developed considerably over the past two decades but remains primarily risk focused. Despite this, growing attention to and work on protective factors or strengths has occurred. In this prospective naturalistic study with repeated observer-rated measures of 27 forensic patients, we tested the role of three potentially important but understudied dynamic protective factors: hope, insight, and resilience, along with a history of criminality, in terms of their impact on violence. Main effects models indicated that higher hopelessness and past criminal convictions were predictive of violence acts; higher resilience was associated with lower violence. In interaction models, hopelessness remained predictive. Importantly, there were significant interactions between resilience and past criminal convictions, with higher levels of resilience leading to lower violence, most amongst those with criminal convictions, and between resilience and hopelessness related emotional distress, in that higher resilience at high levels of patient acknowledged emotional distress due to hopelessness led to lower violence. Findings indicate the importance of focusing on strengths or protective factors in the assessment of risk and treatment planning for forensic patients. Despite the small sample, the repeated measures design was feasible and informative. Keywords: forensic mental health, discharge, repeated measures, insight, hopelessness, resilience, risk assessment

• Linge, Anita; Jensen, Chris; Laake, Petter & Bjørkly, Stål (2021). Lifestyle and work-related factors associated with work ability and work participation for people with obesity: A prospective observational study after vocational rehabilitation. Diabetes, Metabolic Syndrome and Obesity. 14, s. 2943–2954. doi: 10.2147/DMSO.S311462. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: We aimed to investigate which changes in the explanatory factors that were associated with positive change in the work ability score (WAS) and degree of work participation (DWP) for participants in a new 1-year vocational rehabilitation (VR) program for people on or at risk of sick leave due to obesity or obesity-related problems. Patients and Methods: This prospective observational study included 95 participants with a body mass index (BMI) above 30 kg/m2. The 1-year multidisciplinary VR program with an integrated work and lifestyle intervention included 4 weeks of inpatient stay followed-up by five meetings. Differences between baseline and 12-month follow-up data were analyzed for the change in explanatory variables WAS, DWP, health-related quality of life (HRQoL), BMI, and return-to-work self-efficacy (RTWSE). The primary outcome was measured by multiple linear regression for predicting WAS and DWP. Results: We found significant changes in WAS (1.51, 95% CI: 0.83 to 2.20, p< 0.001), DWP (18.69, 95% CI: 8.35 to 29.02, p< 0.001), HRQoL (2.57, 95% CI: 1.35 to 3.79, p< 0.001), BMI (− 2.33, 95% CI: − 3.10 to − 1.56, p< 0.001), and in RTWSE (15.89, 95% CI: 4.07 to 27.71, p = 0.009). Regression analysis yielded a strong association between WAS at 12-month follow-up with an increase in HRQoL (β=0.27, 95% CI: 0.16 to 0.38, p< 0.001) and WAS baseline (β=0.49, 95% CI: 0.28 to 0.71, p< 0.001). Further, regression analysis demonstrated a strong association between DWP at 12-month follow-up with return-to-work expectancy (RTWEXP) (β=− 10.62, 95% CI: − 15.25 to − 6.03, p< 0.001). Conclusion: The results indicate positive changes in WAS, DWP, HRQoL, BMI, and RTWSE from baseline to 12-month follow-up. For people with BMI above 30 kg/m2, changes in HRQoL are important for an increase in WAS, and a high RTWEXP is essential to achieve work participation. Future studies examining VR programs with lifestyle interventions for people with obesity are recommended.

• Brevik, Thea Beate; Trope, Ameli; Laake, Petter & Bjørkly, Stål (2021). Does women’s screening history have any impact on mammography screening attendance after tailored education? : A systematic review and meta-analysis. Medical Care. ISSN 0025-7079. 59(10), s. 893–900. doi: 10.1097/MLR.0000000000001576. Fulltekst i vitenarkiv Vis sammendrag

  Background: Many ethnic minority women have low attendance at breast cancer screening. Objectives: This brief report explores whether women’s screening histories impact mammography screening attendance after tailored education. Research Design: Systematic searches were conducted in 5 databases. Randomized controlled trials of educational interventions tailored to ethnic minority women that measured attendance at mammography screening were eligible for inclusion. Data extraction and risk of bias assessment were performed independently. Data were combined in a meta-analysis by using random effects models. Heterogeneity was estimated by using I2 statistics. Results: Six studies with 3521 women were eligible for inclusion. The D+L pooled risk ratio (RR) for mammography attendance for never screened participants was 1.54 (95% confidence interval, 1.24–1.91; P<0.001), with low heterogeneity (I2=27.1%, P=0.231). The D+L pooled risk ratio for attendance for ever screened participants was 1.26 (95% confidence interval, 1.11–1.43; P<0.001), with low heterogeneity (I2=35.5%, P=0.213). Conclusions: Tailored education increased attendance at mammography by 54% among never screened women and 26% among ever screened women. Although these findings must be interpreted with caution, the findings suggest that women’s screening history is an important and ignored variable that affects how effective tailored education is on mammography screening attendance.

• Mundal, Ingunn Pernille; Laake, Petter; Mezzich, Juan; Bjørkly, Stål & Cabrera, Mariela Loreto Lara (2021). Assessment of the quality of life in parents of children with ADHD : validation of the Multicultural Quality of Life in Norwegian pediatric mental health settings. Frontiers in Psychology. 12:638006, s. 1–10. doi: 10.3389/fpsyg.2021.638006. Fulltekst i vitenarkiv Vis sammendrag

  Background: The brief generic Multicultural Quality of Life Index (MQLI) is a culturally informed self-report 10-item questionnaire used to measure health-related quality of life (QoL). QoL is an important outcome measure in guiding healthcare and is held as a substantial parameter to evaluate the effectiveness of healthcare. Attention Deficit Hyperactivity Disorder (ADHD) in children might negatively influence the parents’ QoL. Having a validated questionnaire to measure QoL for this population will therefore be a vital first step in guiding healthcare for parents of children with ADHD. We aimed to examine the reliability and validity of the Norwegian version of the MQLI in a sample of parents of children with ADHD. Methods: In a cross-sectional study, 128 parents of children with ADHD were recruited from four outpatient clinics within the Child and Adolescents Mental Health Services (CAMHS) in Norway. They completed the MQLI along with an alternative well-being scale, the Five-item World Health Organization Well-being Index (WHO-5), and a form including demographic variables. Reliability and validity of the MQLI were examined. We conducted a factor analysis and calculated internal consistency and the correlation between the MQLI and the WHO-5. Results: Factor analysis of the parents reported MQLI yielded a one-factor solution. For the MQLI, Cronbach’s alpha was 0.73. The correlation between the two measures of MQLI and WHO-5 was high (r = 0.84), reflecting convergent validity since the association between the two measures was strong. Conclusion: Results from this study support the reliability and validity of the Norwegian version of the MQLI for assessment of quality of life in parents of children with ADHD with good psychometric properties. Study findings support the use of the questionnaire in CAMHS.

• Bjørkly, Stål; Laake, Petter; Roaldset, John Olav & Douglas, Kevin Stewart (2021). The Safe pilot study : a prospective naturalistic study with repeated measures design to test the psychosis - violence link in and after discharge from forensic facilities. Psychiatry Research. ISSN 0165-1781. 298(April), s. 1–7. doi: 10.1016/j.psychres.2021.113793. Fulltekst i vitenarkiv Vis sammendrag

  The research evidence is very strong for high recidivism rates of violence after discharge from forensic facilities. Big data research has found that a substantial proportion of the forensic population with relapse into violence has a psychosis diagnosis and a criminal record. However, more research on the association between psychotic symptoms and violence may inform and enhance risk assessment, prevention, and treatment. We conducted a prospective naturalistic study with a repeated measures design in a sample of 22 psychotic patients during follow-up after discharge from forensic mental health facilities. We had three aims: to test the predictive validity of three psychotic symptom scales for violence, to analyze main and interaction effects between psychotic symptoms and previous criminal conviction, and to explore the feasibility and potential benefit of the repeated measures design for prospective follow-up research. Interpreted within the limitation of the small sample size, the results were promising for all scales, particularly for adjusted effects without interaction. Two scales remained significant when their interaction with criminal conviction was adjusted. This indicates that risk judgment of psychotic patients with criminal conviction can be improved by adding measurement of fluctuations in psychotic symptoms. The repeated measures design was instrumental in this research. Keywords: forensic mental health, repeated measures, discharge, psychotic symptoms, criminality, violence

• Linge, Anita; Jensen, Chris; Laake, Petter & Bjørkly, Stål (2021). Changes to body mass index, work self-efficacy, health-related quality of life, and work participation in people with obesity after vocational rehabilitation : a prospective observational study. BMC Public Health. 21, s. 1–11. doi: 10.1186/s12889-021-10954-y. Fulltekst i vitenarkiv Vis sammendrag

  Background People on or at risk of sick leave from work due to obesity or obesity-related problems participated in a new vocational rehabilitation (VR). The study aimed to examine the outcome changes in the participants’ health-related quality of life (HRQoL), body mass index (BMI), return to work self-efficacy (RTWSE), work ability scale (WAS) and degree of work participation (DWP) after their participation in the 12-month VR programme. The secondary aim was to examine associations between the outcome changes and HRQoL at 12-month follow-up, measured with the HRQoL 15D instrument (15D). Methods This prospective observational study included 95 participants. The one-year multidisciplinary VR programme with an integrated work and lifestyle intervention included 4 weeks of inpatient stay followed-up by 5 meetings. A paired sample t-test was used to examine changes in HRQoL, BMI, RTWSE, WAS, and DWP between baseline and the 12-month follow-up. Multiple linear regression analyses explored associations between changes in HRQoL and the outcome variables. Results The participants achieved statistically significant changes in HRQoL (2.57, 95% CI: 1.35 to 3.79), BMI (− 2.33, 95% CI: − 3.10 to − 1.56), RTWSE (15.89, 95% CI: 4.07 to 27.71), WAS (1.51, 95% CI: 0.83 to 2.20) and DWP (18.69, 95% CI: 8.35 to 29.02). At 12 months, a significant association was found between HRQoL and BMI (B = − 0.34, 95% CI: − 0.65 to − 0.04), RTWSE (B = 0.02, 95% CI: 0.004 to 0.04), WAS (B = 0.91, 95% CI: 0.55 to 1.28), DWP (B = − 0.02, 95% CI: − 0.04 to 0.001) and work absence (B = − 0.01, 95% CI: − 0.02 to − 0.002). The regression model explained 71.8% of the HRQoL variance. Conclusion The results indicated positive changes in HRQoL, BMI, RTWSE, WAS and DWP from baseline to the 12-month follow-up. Factors associated with HRQoL at the 12-month follow-up were decreased BMI, increased RTWSE, improved WAS and reduced work absence. Future studies examining VR programmes with lifestyle interventions for people with obesity are recommended.

• Løvgren, Pia Jorde; Laake, Petter; Reitan, Solveig Merete Klæbo & Narud, Kjersti (2020). Assessing psychotic symptoms in forensic evaluations of criminal responsibility–a pilot study using Positive And Negative Syndrome Scale. Journal of Forensic Psychiatry & Psychology. ISSN 1478-9949. 31(4), s. 490–502. doi: 10.1080/14789949.2020.1771402. Fulltekst i vitenarkiv Vis sammendrag

  Description of symptoms and signs related to psychotic disorders at the time of the crime is essential in forensic evaluations of legal insanity. Knowledge of the content of forensic reports is important to improve and secure their quality. Here we report the findings of a pilot study using PANSS as an instrument to assess descriptions of psychotic symptoms in forensic psychiatric reports. Three experienced psychiatrists assessed 20 forensic reports focusing on forensic experts’ descriptions of the defendant’s mental state at the time of the observation and at the time of the alleged crime. PANSS was evaluated as a tool for examining relevant psychotic symptoms, and interrater reliability was calculated. Interrater reliability was satisfactory. It varied based on the percentage of symptoms not described in the reports and on the type of symptom. At both times more symptoms were described from the positive scale of PANSS, than from the negative and the general scale. This pilot study shows that PANSS can be used as an instrument for the structured assessment of psychotic symptoms in written forensic reports and indicates that psychotic symptoms at the time of the alleged crime are poorly described.

• Brevik, Thea Beate; Laake, Petter & Bjørkly, Stål (2020). Effect of culturally tailored education on attendance at mammography and the Papanicolaou test. Health Services Research (HSR). ISSN 0017-9124. 55(3), s. 457–468. doi: 10.1111/1475-6773.13271. Fulltekst i vitenarkiv Vis sammendrag

  Objectives To determine the effectiveness of culturally tailored education on attendance at breast and cervical cancer screening among ethnic minority women. Data Sources Systematic database searches in Ovid MEDLINE, ProQuest, PubMed, PsycINFO, and Cochrane CENTRAL. Study Design Randomized controlled trials (RCTs) of culturally tailored educational interventions to ethnic minority women in Western countries were investigated for a meta‐analysis. RCTs that assessed attendance at mammography or the Papanicolaou test (Pap test) were eligible for inclusion. Data Collection Methods Study characteristics and results were extracted separately. Independent raters assessed risk of bias by using Cochrane Collaboration's tool. Principal Findings Seven RCTs (n = 4246) were included in the meta‐analysis of mammography attendance, and four RCTs (n = 1750) were included in the meta‐analysis of Pap test attendance. The effect of culturally tailored educational interventions on attendance at mammography was an increase of 18 percent (RR = 1.18, 95% CI, 1.09‐1.28, P < .001), with low heterogeneity (I2 = 30.0, P = .237), and a 54 percent increase at the Pap test (RR = 1.54, 95% CI, 1.14‐2.09, P = .005), with substantial heterogeneity (I2 = 75.9%, P = .001). Conclusions Interpreted within the limitations set by the low number of studies and substantial heterogeneity for the Pap test, findings from the current meta‐analyses indicate that culturally tailored educational interventions may increase attendance of ethnic minority women at breast and cervical cancer screenings. There is a need for more studies, in particular RCTs conducted outside the United States, to determine if such findings are similar in other countries. Keywords: ethnic groups, health education, mammography, meta‐analysis, Papanicolaou test

• Lydersen, Stian; Fagerland, Morten & Laake, Petter (2019). Alternativer til Fishers eksakte test. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 139(14), s. 1397–1397. doi: 10.4045/tidsskr.19.0238. Fulltekst i vitenarkiv Vis sammendrag

  Dersom man vil undersøke om det er en sammenheng mellom to variabler i en krysstabell, kan Pearsons khikvadrattest brukes for store utvalg (1), mens Fishers eksakte test er det tradisjonelle alternativet for små utvalg (2). Tabell 1 viser resultatet av et randomisert kontrollert forsøk (3). Nullhypotesen er at sannsynligheten for suksess (24 timers overlevelse) er den samme for de to behandlingene, og alternativhypotesen er at det er forskjell i overlevelse mellom behandlingene. Utvalget er for lite til at Pearsons khikvadrattest kan anbefales, og den tradisjonelle løsningen er å bruke Fishers eksakte test, som gir en tosidig p-verdi på 0,054 (2). Denne testen betinger på kolonnesummene, dvs. at p-verdien beregnes som om det totale antallet suksesser var forutbestemt hvis nullhypotesen er riktig.

• Kristoffersen, Doris Tove; Helgeland, Jon; Clench-Aas, Jocelyne; Laake, Petter & Veierød, Marit Bragelien (2018). Observed to expected or logistic regression to identify hospitals with high or low 30-day mortality? PLOS ONE. 13(4). doi: 10.1371/journal.pone.0195248. Fulltekst i vitenarkiv Vis sammendrag

  Introduction A common quality indicator for monitoring and comparing hospitals is based on death within 30 days of admission. An important use is to determine whether a hospital has higher or lower mortality than other hospitals. Thus, the ability to identify such outliers correctly is essential. Two approaches for detection are: 1) calculating the ratio of observed to expected number of deaths (OE) per hospital and 2) including all hospitals in a logistic regression (LR) comparing each hospital to a form of average over all hospitals. The aim of this study was to compare OE and LR with respect to correctly identifying 30-day mortality outliers. Modifications of the methods, i.e., variance corrected approach of OE (OE-Faris), bias corrected LR (LR-Firth), and trimmed mean variants of LR and LR-Firth were also studied. Materials and methods To study the properties of OE and LR and their variants, we performed a simulation study by generating patient data from hospitals with known outlier status (low mortality, high mortality, non-outlier). Data from simulated scenarios with varying number of hospitals, hospital volume, and mortality outlier status, were analysed by the different methods and compared by level of significance (ability to falsely claim an outlier) and power (ability to reveal an outlier). Moreover, administrative data for patients with acute myocardial infarction (AMI), stroke, and hip fracture from Norwegian hospitals for 2012–2014 were analysed. Results None of the methods achieved the nominal (test) level of significance for both low and high mortality outliers. For low mortality outliers, the levels of significance were increased four- to fivefold for OE and OE-Faris. For high mortality outliers, OE and OE-Faris, LR 25% trimmed and LR-Firth 10% and 25% trimmed maintained approximately the nominal level. The methods agreed with respect to outlier status for 94.1% of the AMI hospitals, 98.0% of the stroke, and 97.8% of the hip fracture hospitals. Conclusion We recommend, on the balance, LR-Firth 10% or 25% trimmed for detection of both low and high mortality outliers

• Wierenga, Lara M.; Sexton, Joseph; Laake, Petter; Giedd, Jay N. & Tamnes, Christian Krog (2018). A Key Characteristic of Sex Differences in the Developing Brain: Greater Variability in Brain Structure of Boys than Girls. Cerebral Cortex. ISSN 1047-3211. 28(8), s. 2741–2751. doi: 10.1093/cercor/bhx154. Fulltekst i vitenarkiv Vis sammendrag

  In many domains, including cognition and personality, greater variability is observed in males than in females in humans. However, little is known about how variability differences between sexes are represented in the brain. The present study tested whether there is a sex difference in variance in brain structure using a cohort of 643 males and 591 females aged between 3 and 21 years. The broad age-range of the sample allowed us to test if variance differences in the brain differ across age. We observed significantly greater male than female variance for several key brain structures, including cerebral white matter and cortex, hippocampus, pallidum, putamen, and cerebellar cortex volumes. The differences were observed at both upper and lower extremities of the distributions and appeared stable across development. These findings move beyond mean levels by showing that sex differences were pronounced for variability, thereby providing a novel perspective on sex differences in the developing brain.

• Bærug, Anne Bergljot; Sletner, Line; Laake, Petter; Fretheim, Atle; Løland, Beate Fossum & Waage, Christin [Vis alle 8 forfattere av denne artikkelen] (2018). Recent gestational diabetes was associated with mothers stopping predominant breastfeeding earlier in a multi-ethnic population. Acta Paediatrica. ISSN 0803-5253. 107(6), s. 1028–1035. doi: 10.1111/apa.14274. Fulltekst i vitenarkiv Vis sammendrag

  Aim: It has previously been shown that breastfeeding may reduce the risk of type 2 diabetes in mothers with recent gestational diabetes mellitus (GDM). This study compared the cessation of predominant breastfeeding in mothers with and without recent GDM in a multi‐ethnic population. Methods: From May 2008 to May 2010, healthy pregnant women attending antenatal care provided by community health services in Eastern Oslo, Norway were recruited. We included 616 women–58% non‐Western–and interviewed and examined them at a mean of 15 and 28 weeks of gestation and 14 weeks’ postpartum. Cox regression models examined the association between GDM, as assessed by the 2013 World Health Organization criteria, and breastfeeding cessation. Results: Overall, 190 of the 616 (31%) mothers had GDM and they ended predominant breastfeeding earlier than mothers without GDM, with an adjusted hazard ratio (aHR) of 1.33 and 95% confidence interval (95% CI) of 1.01–1.77. Mothers of South Asian origin ended predominant breastfeeding earlier than Western European mothers in the adjusted analysis (aHR 1.53, 95% CI: 1.04–2.25), but Middle Eastern mothers did not. Conclusion: Recent gestational diabetes was associated with earlier cessation of predominant breastfeeding in Western European and non‐Western women.

• Bærug, Anne Bergljot; Laake, Petter; Løland, Beate Fossum; Tylleskär, Thorkild; Tufte, Elisabeth & Fretheim, Atle (2017). Explaining socioeconomic inequalities in exclusive breast feeding in Norway. Archives of Disease in Childhood. ISSN 0003-9888. 102(8), s. 708–714. doi: 10.1136/archdischild-2016-312038. Fulltekst i vitenarkiv
• Paur, Ingvild; Lilleby, Wolfgang; Bøhn, Siv Kjølsrud; Hulander, Erik; Klein, Willibrord & Vlatkovic, Ljiljana [Vis alle 19 forfattere av denne artikkelen] (2016). Tomato-based randomized controlled trial in prostate cancer patients: Effect on PSA. Clinical Nutrition. ISSN 0261-5614. 36(3), s. 672–679. doi: 10.1016/j.clnu.2016.06.014. Fulltekst i vitenarkiv Vis sammendrag

  Background & aims: The effect of lycopene-containing foods in prostate cancer development remains undetermined. We tested whether a lycopene-rich tomato intervention could reduce the levels of prostate specific antigen (PSA) in prostate cancer patients. Methods: Prior to their curative treatment, 79 patients with prostate cancer were randomized to a nutritional intervention with either 1) tomato products containing 30 mg lycopene per day; 2) tomato products plus selenium, omega-3 fatty acids, soy isoflavones, grape/pomegranate juice, and green/black tea (tomato-plus); or 3) control diet for 3 weeks. Results: The main analysis, which included patients in all risk categories, did not reveal differences in changes of PSA-values between the intervention and control groups. Post-hoc, exploratory analyses within intermediate risk (n = 41) patients based on tumor classification and Gleason score post-surgery, revealed that median PSA decreased significantly in the tomato group as compared to controls (−2.9% and +6.5% respectively, p = 0.016). In separate post-hoc analyses, we observed that median PSA-values decreased by 1% in patients with the highest increases in plasma lycopene, selenium and C20:5 n-3 fatty acid, compared to an 8.5% increase in the patients with the lowest increase in lycopene, selenium and C20:5 n-3 fatty acid (p = 0.003). Also, PSA decreased in patients with the highest increase in lycopene alone (p = 0.009). Conclusions: Three week nutritional interventions with tomato-products alone or in combination with selenium and n-3 fatty acids lower PSA in patients with non-metastatic prostate cancer. Our observation suggests that the effect may depend on both aggressiveness of the disease and the blood levels of lycopene, selenium and omega-3 fatty acids.

• Fagerland, Morten; Lydersen, Stian & Laake, Petter (2015). Recommended confidence intervals for two independent binomial proportions. Statistical Methods in Medical Research. ISSN 0962-2802. 24(2), s. 224–254. doi: 10.1177/0962280211415469. Fulltekst i vitenarkiv
• Buonaccorsi, John P.; Dalen, Ingvild; Laake, Petter; Hjartåker, Anette; Engeset, Dagrun & Thoresen, Magne (2015). Sensitivity of regression calibration to non-perfect validation data with application to the Norwegian Women and Cancer Study. Statistics in Medicine. ISSN 0277-6715. 34(8), s. 1389–1403. doi: 10.1002/sim.6420. Fulltekst i vitenarkiv
• Buonaccorsi, John P.; Laake, Petter & Veierød, Marit Bragelien (2014). On the power of the Cochran-Armitage test for trend in the presence of misclassification. Statistical Methods in Medical Research. ISSN 0962-2802. 3, s. 218–243. doi: 10.1177/0962280211406424. Fulltekst i vitenarkiv
• Fagerland, Morten; Lydersen, Stian & Laake, Petter (2014). Recommended tests and confidence intervals for paired binomial proportions. Statistics in Medicine. ISSN 0277-6715. 33(16), s. 2850–2875. doi: 10.1002/sim.6148. Fulltekst i vitenarkiv
• Birkeflet, Oddveig; Laake, Petter & Vøllestad, Nina Køpke (2014). Poor multi-rater reliability in TCM pattern diagnoses and variation in the use of symptoms to obtain a diagnosis. Acupuncture in Medicine. ISSN 0964-5284. 32(4), s. 325–332. doi: 10.1136/acupmed-2013-010473. Fulltekst i vitenarkiv
• Lehre, Anne- Catherine W G; Laake, Petter & Sexton, Joseph Andrew (2014). Using Quantile Distance Functions to Assess Inter- and Intrasex Variability in PISA Achievement Scores. I Strietholt, Rolf; Bos, Wilfred; Gustafsson, Jan-Eric & Rosén, Monica (Red.), Educational Policy Evaluation through International Comparative Assessments. Waxmann Verlag. ISSN 9783830930914. s. 177–190. Fulltekst i vitenarkiv
• Buonaccorsi, John P.; Laake, Petter & Veierød, Marit Bragelien (2014). On the power of the Cochran-Armitage test for trend in the presence of misclassification. Statistical Methods in Medical Research. ISSN 0962-2802. 23(3), s. 218–243. doi: 10.1177/0962280211406424. Fulltekst i vitenarkiv
• Fagerland, Morten; Lydersen, Stian & Laake, Petter (2013). The McNemar test for binary matched-pairs data: mid-p and asymptotic are better than exact conditional. BMC Medical Research Methodology. 13. doi: 10.1186/1471-2288-13-91. Fulltekst i vitenarkiv Vis sammendrag

  Background Statistical methods that use the mid-p approach are useful tools to analyze categorical data, particularly for small and moderate sample sizes. Mid-p tests strike a balance between overly conservative exact methods and asymptotic methods that frequently violate the nominal level. Here, we examine a mid-p version of the McNemar exact conditional test for the analysis of paired binomial proportions. Methods We compare the type I error rates and power of the mid-p test with those of the asymptotic McNemar test (with and without continuity correction), the McNemar exact conditional test, and an exact unconditional test using complete enumeration. We show how the mid-p test can be calculated using eight standard software packages, including Excel. Results The mid-p test performs well compared with the asymptotic, asymptotic with continuity correction, and exact conditional tests, and almost as good as the vastly more complex exact unconditional test. Even though the mid-p test does not guarantee preservation of the significance level, it did not violate the nominal level in any of the 9595 scenarios considered in this article. It was almost as powerful as the asymptotic test. The exact conditional test and the asymptotic test with continuity correction did not perform well for any of the considered scenarios. Conclusions The easy-to-calculate mid-p test is an excellent alternative to the complex exact unconditional test. Both can be recommended for use in any situation. We also recommend the asymptotic test if small but frequent violations of the nominal level is acceptable.

• Lehre, Anne- Catherine W G; Laake, Petter & Sexton, Joseph (2013). Differences in birth weight by sex using adjusted quantile distance functions. Statistics in Medicine. ISSN 0277-6715. 32(17), s. 2962–2970. doi: 10.1002/sim.5744. Fulltekst i vitenarkiv
• Ringdal, Kjetil G.; Skaga, Nils Oddvar; Steen, Petter Andreas; Hestnes, Morten; Laake, Petter & Jones, J. Mary [Vis alle 7 forfattere av denne artikkelen] (2013). Classification of comorbidity in trauma: The reliability of pre-injury ASA physical status classification. Injury. ISSN 0020-1383. 44(1), s. 29–35. doi: 10.1016/j.injury.2011.12.024. Fulltekst i vitenarkiv
• Karlsen, Anette; Svendsen, Mette; Seljeflot, Ingebjørg; Laake, Petter; Duttaroy, Asim K. & Drevon, Christian A [Vis alle 9 forfattere av denne artikkelen] (2013). Kiwifruit decreases blood pressure and whole-blood platelet aggregation in male smokers. Journal of Human Hypertension. ISSN 0950-9240. 27(2), s. 126–130. doi: 10.1038/jhh.2011.116. Fulltekst i vitenarkiv
• Veierød, Marit Bragelien; Lydersen, Stian & Laake, Petter (2012). Design and analysis. I Veierød, Marit Bragelien; Lydersen, Stian & Laake, Petter (Red.), Medical statistics in clinical and epidemiological research. Gyldendal Akademisk. ISSN 9788205399594. s. 23–44. Fulltekst i vitenarkiv
• Lehre, Anne- Catherine W G; Hansen, Arvid Hedley; Lehre, Knut Petter Dæhlin & Laake, Petter (2012). Effects of the 2003 Quality Reform on Gender Gaps in Student Learning Outcomes in Norwegian Higher Education. Scandinavian Journal of Educational Research. ISSN 0031-3831. 58(3), s. 315–336. doi: 10.1080/00313831.2012.732602. Fulltekst i vitenarkiv
• Fagerland, Morten; Eide, Geir Egil & Laake, Petter (2012). Linear regression. I Veierød, Marit Bragelien; Lydersen, Stian & Laake, Petter (Red.), Medical statistics in clinical and epidemiological research. Gyldendal Akademisk. ISSN 9788205399594. s. 126–166. Fulltekst i vitenarkiv
• Lydersen, Stian; Fagerland, Morten & Laake, Petter (2012). Categorical data and contingency tables. I Veierød, Marit Bragelien; Lydersen, Stian & Laake, Petter (Red.), Medical statistics in clinical and epidemiological research. Gyldendal Akademisk. ISSN 9788205399594. s. 48–89. Fulltekst i vitenarkiv
• Birkeflet, Oddveig; Laake, Petter & Vøllestad, Nina Køpke (2012). Traditional Chinese medicine patterns and recommended acupuncture points in infertile and fertile women. Acupuncture in Medicine. ISSN 0964-5284. 30(1), s. 12–16. doi: 10.1136/acupmed-2011-010089. Fulltekst i vitenarkiv
• Sexton, Joseph; Blomhoff, Rune; Karlsen, Anette & Laake, Petter (2012). Adaptive combination of dependent tests. Computational Statistics & Data Analysis. ISSN 0167-9473. 56(6), s. 1935–1943. doi: 10.1016/j.csda.2011.11.018. Fulltekst i vitenarkiv
• Sexton, Joseph & Laake, Petter (2012). Boosted coefficient models. Statistics and computing. ISSN 0960-3174. 22(4), s. 867–876. doi: 10.1007/s11222-011-9253-0. Fulltekst i vitenarkiv
• Kristoffersen, Doris Tove; Helgeland, Jon; Clench-Aas, Jocelyne; Laake, Petter & Veierød, Marit Bragelien (2012). Comparing hospital mortality - how to count does matter for patients hospitalized for acute myocardial infarction (AMI), stroke and hip fracture. BMC Health Services Research. 12. doi: 10.1186/1472-6963-12-364. Fulltekst i vitenarkiv Vis sammendrag

  Background Mortality is a widely used, but often criticised, quality indicator for hospitals. In many countries, mortality is calculated from in-hospital deaths, due to limited access to follow-up data on patients transferred between hospitals and on discharged patients. The objectives were to: i) summarize time, place and cause of death for first time acute myocardial infarction (AMI), stroke and hip fracture, ii) compare case-mix adjusted 30-day mortality measures based on in-hospital deaths and in-and-out-of hospital deaths, with and without patients transferred to other hospitals. Methods Norwegian hospital data within a 5-year period were merged with information from official registers. Mortality based on in-and-out-of-hospital deaths, weighted according to length of stay at each hospital for transferred patients (W30D), was compared to a) mortality based on in-and-out-of-hospital deaths excluding patients treated at two or more hospitals (S30D), and b) mortality based on in-hospital deaths (IH30D). Adjusted mortalities were estimated by logistic regression which, in addition to hospital, included age, sex and stage of disease. The hospitals were assigned outlier status according to the Z-values for hospitals in the models; low mortality: Z-values below the 5-percentile, high mortality: Z-values above the 95-percentile, medium mortality: remaining hospitals. Results The data included 48 048 AMI patients, 47 854 stroke patients and 40 142 hip fracture patients from 55, 59 and 58 hospitals, respectively. The overall relative frequencies of deaths within 30 days were 19.1% (AMI), 17.6% (stroke) and 7.8% (hip fracture). The cause of death diagnoses included the referral diagnosis for 73.8-89.6% of the deaths within 30 days. When comparing S30D versus W30D outlier status changed for 14.6% (AMI), 15.3% (stroke) and 36.2% (hip fracture) of the hospitals. For IH30D compared to W30D outlier status changed for 18.2% (AMI), 25.4% (stroke) and 27.6% (hip fracture) of the hospitals. Conclusions Mortality measures based on in-hospital deaths alone, or measures excluding admissions for transferred patients, can be misleading as indicators of hospital performance. We propose to attribute the outcome to all hospitals by fraction of time spent in each hospital for patients transferred between hospitals to reduce bias due to double counting or exclusion of hospital stays.

• Lehre, Anne- Catherine W G; Rowley, Nicole; Zhou, Yun; Holmseth, Silvia; Guo, Chungang & Holen, Torgeir [Vis alle 16 forfattere av denne artikkelen] (2011). Deletion of the betaine-GABA transporter (BGT1; slc6a12) gene does not affect seizure thresholds of adult mice. Epilepsy Research. ISSN 0920-1211. 95(1-2), s. 70–81. doi: 10.1016/j.eplepsyres.2011.02.014. Fulltekst i vitenarkiv
• Birkeflet, Oddveig; Laake, Petter & Vøllestad, Nina Køpke (2011). Low inter-rater reliability in traditional Chinese medicine for female infertility. Acupuncture in Medicine. ISSN 0964-5284. 29(1), s. 51–57. doi: 10.1136/aim.2010.003186. Fulltekst i vitenarkiv
• Karlsen, Anette; Svendsen, Mette; Seljeflot, Ingebjørg; Sommernes, Mary-Ann; Sexton, Joseph & Brevik, Asgeir [Vis alle 23 forfattere av denne artikkelen] (2011). Compliance, tolerability and safety of two antioxidant-rich diets: a randomised controlled trial in male smokers. British Journal of Nutrition. ISSN 0007-1145. 106(4), s. 557–571. doi: 10.1017/S0007114511000353. Fulltekst i vitenarkiv
• Yasein, Nadia Nabil Haj; Vindedal, Gry Fluge; Eilert-Olsen, Martine; Gundersen, Georg Andreas; Skare, Øivind & Laake, Petter [Vis alle 11 forfattere av denne artikkelen] (2011). Glial-conditional deletion of aquaporin-4 (Aqp4) reduces blood-brain water uptake and confers barrier function on perivascular astrocyte endfeet. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 108(43), s. 17815–17820. doi: 10.1073/pnas.1110655108. Fulltekst i vitenarkiv
• Kjelsberg, Ellen & Laake, Petter (2010). Is the high mortality risk in sentenced offenders independent of previous imprisonment? European Journal of Epidemiology (EJE). ISSN 0393-2990. 25(4), s. 237–243. doi: 10.1007/s10654-010-9436-6. Fulltekst i vitenarkiv
• Karlsen, Anette; Paur, Ingvild; Bøhn, Siv Kjølsrud; Sakhi, Amrit Kaur; Borge, Grethe iren andersen & Serafini, Mauro [Vis alle 10 forfattere av denne artikkelen] (2010). Bilberry juice modulates plasma concentration of NF-kappa B related inflammatory markers in subjects at increased risk of CVD. European Journal of Nutrition. ISSN 1436-6207. 49(6), s. 345–355. doi: 10.1007/s00394-010-0092-0. Fulltekst i vitenarkiv
• Frøslie, Kathrine Frey; Røislien, Jo; Laake, Petter; Henriksen, Tore; Qvigstad, Elisabeth & Veierød, Marit Bragelien (2010). Categorisation of continuous exposure variables revisited. A response to the Hyperglycaemia and Adverse Pregnancy Outcome (HAPO) Study. BMC Medical Research Methodology. 10. doi: 10.1186/1471-2288-10-103. Fulltekst i vitenarkiv Vis sammendrag

  Background Although the general statistical advice is to keep continuous exposure variables as continuous in statistical analyses, categorisation is still a common approach in medical research. In a recent paper from the Hyperglycaemia and Adverse Pregnancy Outcome (HAPO) Study, categorisation of body mass index (BMI) was used when analysing the effect of BMI on adverse pregnancy outcomes. The lowest category, labelled "underweight", was used as the reference category. Methods The present paper gives a summary of reasons for categorisation and methodological drawbacks of this approach. We also discuss the choice of reference category and alternative analyses. We exemplify our arguments by a reanalysis of results from the HAPO paper. Results Categorisation of continuous exposure data results in loss of power and other methodological challenges. An unfortunate choice of reference category can give additional lack of precision and obscure the interpretation of risk estimates. A highlighted odds ratio (OR) in the HAPO study is the OR for birth weight >90th percentile for women in the highest compared to the lowest BMI category ("obese class III" versus "underweight"). This estimate was OR = 4.55 and OR = 3.52, with two different multiple logistic regression models. When using the "normal weight" category as the reference, our corresponding estimates were OR = 2.03 and OR = 1.62, respectively. Moreover, our choice of reference category also gave narrower confidence intervals. Summary Due to several methodological drawbacks, categorisation should be avoided. Modern statistical analyses should be used to analyse continuous exposure data, and to explore non-linear relations. If continuous data are categorised, special attention must be given to the choice of reference category.

• Bøhn, Siv Kjølsrud; Myhrstad, Mari Charlotte; Thoresen, Magne; Holden, Marit; Karlsen, Anette & Tunheim, Siv Haugen [Vis alle 17 forfattere av denne artikkelen] (2010). Blood cell gene expression associated with cellular stress defense is modulated by antioxidant-rich food in a randomised controlled clinical trial of male smokers. BMC Medicine. 8. doi: 10.1186/1741-7015-8-54. Fulltekst i vitenarkiv Vis sammendrag

  Background Plant-based diets rich in fruit and vegetables can prevent development of several chronic age-related diseases. However, the mechanisms behind this protective effect are not elucidated. We have tested the hypothesis that intake of antioxidant-rich foods can affect groups of genes associated with cellular stress defence in human blood cells. Trial registration number: NCT00520819 http://clinicaltrials.gov. Methods In an 8-week dietary intervention study, 102 healthy male smokers were randomised to either a diet rich in various antioxidant-rich foods, a kiwifruit diet (three kiwifruits/d added to the regular diet) or a control group. Blood cell gene expression profiles were obtained from 10 randomly selected individuals of each group. Diet-induced changes on gene expression were compared to controls using a novel application of the gene set enrichment analysis (GSEA) on transcription profiles obtained using Affymetrix HG-U133-Plus 2.0 whole genome arrays. Results Changes were observed in the blood cell gene expression profiles in both intervention groups when compared to the control group. Groups of genes involved in regulation of cellular stress defence, such as DNA repair, apoptosis and hypoxia, were significantly upregulated (GSEA, FDR q-values < 5%) by both diets compared to the control group. Genes with common regulatory motifs for aryl hydrocarbon receptor (AhR) and AhR nuclear translocator (AhR/ARNT) were upregulated by both interventions (FDR q-values < 5%). Plasma antioxidant biomarkers (polyphenols/carotenoids) increased in both groups. Conclusions The observed changes in the blood cell gene expression profiles suggest that the beneficial effects of a plant-based diet on human health may be mediated through optimization of defence processes.

• Sexton, Joseph & Laake, Petter (2009). Standard errors for bagged and random forest estimators. Computational Statistics & Data Analysis. ISSN 0167-9473. 53(3), s. 801–811. doi: 10.1016/j.csda.2008.08.007. Fulltekst i vitenarkiv
• Dalen, Ingvild; Buonaccorsi, JP; Sexton, Joseph; Laake, Petter & Thoresen, Magne (2009). Correction for misclassification of a categorized exposure in binary regression using replication data. Statistics in Medicine. ISSN 0277-6715. 28(27), s. 3386–3410. doi: 10.1002/sim.3712. Fulltekst i vitenarkiv
• Sexton, Joseph & Laake, Petter (2009). Stochastic Approximation Boosting for Incomplete Data Problems. Biometrics. ISSN 0006-341X. 65(4), s. 1156–1163. doi: 10.1111/j.1541-0420.2009.01202.x. Fulltekst i vitenarkiv
• Lehre, Anne- Catherine W G; Hansen, Arvid Hedley & Laake, Petter (2009). Gender and the 2003 Quality Reform in higher education in Norway. Higher Education. ISSN 0018-1560. 58(5), s. 585–597. doi: 10.1007/s10734-009-9211-3. Fulltekst i vitenarkiv
• Lehre, Anne- Catherine W G; Lehre, Knut Petter Dæhlin; Laake, Petter & Danbolt, Niels Christian (2009). Greater Intrasex Phenotype Variability in Males Than in Females is a Fundamental Aspect of the Gender Differences in Humans. Developmental Psychobiology. ISSN 0012-1630. 51(2), s. 198–206. doi: 10.1002/dev.20358. Fulltekst i vitenarkiv
• Lydersen, Stian; Fagerland, MW & Laake, P (2009). Recommended tests for association in 2 x 2 tables. Statistics in Medicine. ISSN 0277-6715. 28(7), s. 1159–1175. doi: 10.1002/sim.3531. Fulltekst i vitenarkiv
• Kaufmann, Walter A.; Ferraguti, Francesco; Fukazawa, Yugo; Kasugai, Yu; Shigemoto, Ryuichi & Laake, Petter [Vis alle 12 forfattere av denne artikkelen] (2009). Large-Conductance Calcium-Activated Potassium Channels in Purkinje Cell Plasma Membranes Are Clustered at Sites of Hypolemmal Microdomains. Journal of Comparative Neurology. ISSN 0021-9967. 515(2), s. 215–230. doi: 10.1002/cne.22066. Fulltekst i vitenarkiv
• Utvik, Jo Kristian; Haglerød, Camilla Margrete; Mylonakou, Maria-Niki; Holen, Torgeir; Kropf, Michel & Hirling, H [Vis alle 11 forfattere av denne artikkelen] (2009). Neuronal enriched endosomal protein of 21 kDa colocalizes with glutamate receptor subunit GLUR2/3 at the postsynaptic membrane. Neuroscience. ISSN 0306-4522. 158(1), s. 96–104. doi: 10.1016/j.neuroscience.2008.11.030. Fulltekst i vitenarkiv
• Haglerød, Camilla Margrete; Kapica, Aida; Boulland, Jean-Luc; Hussain, Suleman; Holen, Torgeir & Skare, Øivind [Vis alle 10 forfattere av denne artikkelen] (2009). Protein interacting with C kinase 1 (PICK1) and GluR2 are associated with presynaptic plasma membrane and vesicles in hippocampal excitatory synapses. Neuroscience. ISSN 0306-4522. 158(1), s. 242–252. doi: 10.1016/j.neuroscience.2008.11.029. Fulltekst i vitenarkiv
• Parr, CL; Hjartaker, A; Hjartåker, Anette; Laake, Petter; Lund, Eiliv & Veierod, MB [Vis alle 7 forfattere av denne artikkelen] (2009). Recall Bias in Melanoma Risk Factors and Measurement Error Effects: A Nested Case-Control Study Within the Norwegian Women and Cancer Study. American Journal of Epidemiology. ISSN 0002-9262. 169(3), s. 257–266. doi: 10.1093/aje/kwn363. Fulltekst i vitenarkiv
• Sexton, Joseph & Laake, Petter (2008). LogitBoost with errors-in-variables. Computational Statistics & Data Analysis. ISSN 0167-9473. 52. doi: 10.1016/j.csda.2007.09.004. Fulltekst i vitenarkiv
• Parr, CL; Hjartåker, Anette; Hjartaker, A; Scheel, Ida; Lund, Eiliv & Laake, Petter [Vis alle 8 forfattere av denne artikkelen] (2008). Comparing methods for handling missing values in food-frequency questionnaires and proposing k nearest neighbours imputation: effects on dietary intake in the Norwegian Women and Cancer study (NOWAC). Public Health Nutrition (PHN). ISSN 1368-9800. 11, s. 361–370. doi: 10.1017/S1368980007000365. Fulltekst i vitenarkiv
• Benestad, Haakon Breien & Laake, Petter (2008). Forskning: metode og planlegging. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Forskning i medisin og biofag. 2. utgave. Gyldendal Akademisk. ISSN 9788205384873. Fulltekst i vitenarkiv
• Thelle, Dag Steinar & Laake, Petter (2008). Epidemiologisk forskning: begreper og metoder. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Forskning i medisin og biofag. 2. utgave. Gyldendal Akademisk. ISSN 9788205384873. Fulltekst i vitenarkiv
• Laake, Petter & Egeland, Thore (2008). Statistisk analyse av kategoriske data. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Forskning i medisin og biofag. 2. utgave. Gyldendal Akademisk. ISSN 9788205384873. Fulltekst i vitenarkiv
• Laake, Petter & Skovlund, Eva (2008). Statistisk analyse av kontinuerlige data. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Forskning i medisin og biofag. 2. utgave. Gyldendal Akademisk. ISSN 9788205384873. Fulltekst i vitenarkiv
• Olsen, Bjørn Reino; Laake, Petter & Ottersen, Ole Petter (2008). Søknad om forskningsmidler. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Forskning i medisin og biofag. 2. utgave. Gyldendal Akademisk. ISSN 9788205384873. Fulltekst i vitenarkiv
• Utne, Peder Heyerdahl; Thelle, Dag Steinar & Laake, Petter (2008). Kvalitetssikring av forskning. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Forskning i medisin og biofag. 2. utgave. Gyldendal Akademisk. ISSN 9788205384873. Fulltekst i vitenarkiv
• Karlsen, Anette; Svendsen, Mette; Brevik, Asgeir; Bøhn, Siv K; Myhrstad, Mari C.W. & Thoresen, Magne [Vis alle 19 forfattere av denne artikkelen] (2008). Dietary intake of antioxidant-rich foods increase plasma antioxidants, enhance DNA repair capacity and reduce blood pressure in smoking, middle-aged men, PhD Thesis. Universitetet i Oslo. Fulltekst i vitenarkiv

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• Fagerland, Morten; Lydersen, Stian & Laake, Petter (2017). Statistical Analysis of Contingency Tables. CRC Press. ISBN 9781466588172. 634 s. Fulltekst i vitenarkiv
• Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (2015). Research in Medical and Biological Sciences: From Planning and Preparation ot Grant Application and Publication. Academic Press. ISBN 9780127999432. 566 s. Fulltekst i vitenarkiv
• Veierød, Marit Bragelien; Lydersen, Stian & Laake, Petter (2012). Medical statistics in clinical and epidemiological research. Gyldendal Akademisk. ISBN 9788205399594. 720 s. Fulltekst i vitenarkiv
• Laake, Petter & Valen, Guro (2008). Fra basalmedisinsk til klinisk forskning. Gyldendal Akademisk. ISBN 9788205384873. 14 s. Fulltekst i vitenarkiv Vis sammendrag

  Boka Forskning i medisin og biofag er grunnbok til Det medisinske fakultets forskerutdannelse, obligatorisk kurs. Innskrevet et nytt kapitel om translasjonsforskning

• Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (2008). Forskning i medisin og biofag. 2. utgave. Gyldendal Akademisk. ISBN 9788205384873. 550 s. Fulltekst i vitenarkiv

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• Brevik, Thea Beate; Laake, Petter; Bjørkly, Stål Kapstø & Vatnar, Solveig Karin Bø (2025). Can an educational intervention on mandatory reporting of intimate partner violence improve health care providers’ knowledge and attitudes? Fulltekst i vitenarkiv
• Brevik, Thea Beate; Laake, Petter; Bjørkly, Stål Kapstø; Leer-Salvesen, Kjartan & Vatnar, Solveig Karin Bø (2025). Correction to: An educational intervention study on mandatory reporting of intimate partner violence_ changes in knowledge and attitudes among healthcare providers (BMC Medical Education, (2024), 24, 1, (1124), 10.1186/s12909-024-06120-8). BMC Medical Education. 25(1). doi: 10.1186/s12909-025-07442-x. Fulltekst i vitenarkiv
• Lydersen, Stian; Fagerland, Morten & Laake, Petter (2019). Fishers eksakte test - hvordan smaker teen? Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 139(13), s. 1292–1292. doi: 10.4045/tidsskr.19.0237. Fulltekst i vitenarkiv Vis sammendrag

  Et enkelt eksperiment med te og melk kan ha inspirert den britiske statistikeren Ronald Aylmer Fisher (1890–1962) til å lage en av verdens mest kjente statistiske tester.

• Sandvig, Heidi Vihovde & Laake, Petter (2019). Ikke faglig begrunnet styrevedtak om fødesammenslåing. Fulltekst i vitenarkiv
• Lydersen, Stian; Fagerland, Morten & Laake, Petter (2019). Pearsons khikvadrattest. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 139(12), s. 1183–1183. doi: 10.4045/tidsskr.18.0125. Fulltekst i vitenarkiv
• Lydersen, Stian; Fagerland, Morten & Laake, Petter (2018). Evaluation of methods for analysis of 2x2 contingency tables. Fulltekst i vitenarkiv Vis sammendrag

  Evaluation of methods for analysis of 2x2 contingency tables Introduction: Literally hundreds of methods for hypothesis tests and confidence intervals for contingency tables are described in the literature. This is the case even for the seemingly simple 2 × 2 table. The Pearson chi squared test, the Fisher exact test, and the Wald confidence interval are widely used methods. Unfortunately, these methods are also commonly used in situations when they perform poorly, and better alternatives exist. Aims: To show how to evaluate and choose appropriate methods for hypothesis testing and confidence interval estimation for 2x2 tables Methods: Important properties of a hypothesis test are the actual significance level and power. Important properties for a confidence interval are coverage probability, expected interval width, and symmetry. We have studied these properties for alternative methods. Conclusion: For large samples, the asymptotic Pearson chi squared test performs well. Yates’s continuity correction should never be used. In small samples, the traditional advice is the Fisher exact test. But unconditional tests are generally more powerful than Fisher’s exact test for small samples. Unconditional tests also preserve the significance level. That is, the actual significance level does not exceed the nominal significance level, which is often 5%. Unconditional tests were but previously disadvantaged by being computationally demanding. Alternatively, Fisher’s exact test with mid-p adjustment is easy to compute, and gives approximately the same results as an unconditional test. The Wald confidence interval is a traditional choice for the difference between two proportions. But its coverage can dip substantially below the nominal coverage, which is usually 95%. The Agresti-Caffo interval and the Newcombe hybrid score interval are also easy to compute with closed form expressions. They have better coverage, and also narrower expected interval width, and better symmetry than the Wald interval. Reference: Fagerland MW, Lydersen S, Laake P (2017). Statistical Analysis of Contingency Tables. Chapman and Hall/CRC.

• Kristoffersen, Doris Tove; Helgeland, Jon; Clench-Aas, Jocelyne; Laake, Petter & Veierød, Marit Bragelien (2016). Type I error and power for detecting hospitals with high or low 30-day mortality. Fulltekst i vitenarkiv
• Benestad, Haakon Breien & Laake, Petter (2015). Research Strategies, Planning and Analysis. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Research in Medical and Biological Sciences: From Planning and Preparation ot Grant Application and Publication.. Academic Press. ISSN 9780127999432. s. 89–104. Fulltekst i vitenarkiv
• Olsen, Bjørn Reino; Laake, Petter & Ottersen, Ole Petter (2015). Guide to Grant Applications. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Research in Medical and Biological Sciences: From Planning and Preparation ot Grant Application and Publication.. Academic Press. ISSN 9780127999432. s. 519–546. Fulltekst i vitenarkiv
• Holm, Søren; Hofmann, Bjørn & Laake, Petter (2015). Ethics and Scientific Conduct. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Research in Medical and Biological Sciences: From Planning and Preparation ot Grant Application and Publication.. Academic Press. ISSN 9780127999432. s. 43–70. Fulltekst i vitenarkiv
• Thelle, Dag Steinar & Laake, Petter (2015). Epidemiology. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Research in Medical and Biological Sciences: From Planning and Preparation ot Grant Application and Publication.. Academic Press. ISSN 9780127999432. s. 275–320. Fulltekst i vitenarkiv
• Laake, Petter & Fagerland, Morten (2015). Statistical Inference. I Laake, Petter; Benestad, Haakon Breien & Olsen, Bjørn Reino (Red.), Research in Medical and Biological Sciences: From Planning and Preparation ot Grant Application and Publication.. Academic Press. ISSN 9780127999432. s. 379–430. Fulltekst i vitenarkiv
• Fagerland, Morten Wang; Lydersen, Stian & Laake, Petter (2015). Confidence Intervals for Two Independent Binomial Proportions. I Balakrishnan, N.; Brandimarte, Paolo; Everitt, Brian S.; Molenberghs, Geert; Piegorsch, Walter W. & Ruggeri, Fabrizio (Red.), Wiley StatsRef: Statistics Reference Online. John Wiley & Sons. ISSN 9781118445112. doi: 10.1002/9781118445112.stat08007. Fulltekst i vitenarkiv
• Benestad, Haakon Breien & Laake, Petter (2014). Dårlig tittel - dårlig manus? Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 134(4), s. 382–382. doi: 10.4045/tidsskr.14.0143. Fulltekst i vitenarkiv
• Lehre, Anne- Catherine W G; Hansen, Arvid Hedley; Lehre, Knut Petter Dæhlin & Laake, Petter (2012). Gender gap in Norwegian Higher Education. Fulltekst i vitenarkiv
• Thelle, Dag S. & Laake, Petter (2011). Fra ammetåke til klarsyn. Fulltekst i vitenarkiv
• Lydersen, Stian; Laake, Petter & Fagerland, Morten (2011). The analysis of 2 x 2 contingency tables-yet again: Author's reply. Statistics in Medicine. ISSN 0277-6715. 30(8), s. 891–892. doi: 10.1002/sim.4135. Fulltekst i vitenarkiv
• Karlsen, Anette; Lilleby, Wolfgang; Klein, Willibrord; Laake, Petter; Fosså, Sophie Dorothea & Eri, Lars Magne [Vis alle 9 forfattere av denne artikkelen] (2010). A phase I/II randomized controlled trial investigating the effects of two dietary intervention strategies in prostate cancer patients. Fulltekst i vitenarkiv
• Lehre, Anne- Catherine W G; Lehre, Knut Petter Dæhlin; Hansen, Arvid Hedley; Laake, Petter & Danbolt, Niels Christian (2010). Gender: Males are more extreme. Fulltekst i vitenarkiv
• Laake, Petter & Thelle, Dag Steinar (2010). Are mid-pregnancy androgen levels negatively associated with breastfeeding? Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 89(5), s. 722–723. doi: 10.3109/00016341003657942. Fulltekst i vitenarkiv
• Karlsen, Anette; Paur, Ingvild; Bøhn, Siv Kjølsrud; Sakhi, Amrit Kaur; Iren, Borge Grethe & Serafini, Mauro [Vis alle 10 forfattere av denne artikkelen] (2009). Bilberry juice modulate plasma concentration of NF- related inflammatory markers in subjects at increased risk of CVD. Fulltekst i vitenarkiv
• Parr, Christine Louise; Hjartåker, Anette; Laake, Petter; Lund, Eiliv & Veierød, Marit Bragelien (2009). Recall bias in melanoma risk factors and measurement error effects: a nested case-control study within the Norwegian Women and Cancer Study. Norsk Epidemiologi, Supplement. ISSN 0803-4206. 19, s. 8–8. Fulltekst i vitenarkiv
• Parr, CL; Hjartaker, A; Hjartåker, Anette; Laake, Petter; Lund, Eiliv & Veierod, MB [Vis alle 7 forfattere av denne artikkelen] (2009). Parr et al. Respond to "Recall Bias in Melanoma". American Journal of Epidemiology. ISSN 0002-9262. 169(3), s. 271–272. doi: 10.1093/aje/kwn356. Fulltekst i vitenarkiv
• Bøhn, Siv Kjølsrud; Myhrstad, Mari Charlotte; Thoresen, Magne; Holden, Marit; Tunheim, Siv Haugen & Karlsen, Anette [Vis alle 16 forfattere av denne artikkelen] (2008). Plant food phytochemicals modulate gene expression in human blood cells. Fulltekst i vitenarkiv
• Lehre, Anne- Catherine W G; Laake, Petter & Danbolt, Niels Christian (2011). Sex matters: Looking into variability. The variability hypothesis, the 2003 Quality Reform in higher education in Norway, and the role of BGT1 in seizure control. Universitetet i Oslo. ISSN 9788282641494. Fulltekst i vitenarkiv
• Roaldset, John Olav; Gøtestam, K Gunnar; Holen, Are; Bjørkly, Stål & Laake, Petter (2010). Risk assessment of violent, suicidal and self-injurious behaviour in acute psychiatry– a bio-psycho-social approach. Norges teknisk-naturvitenskapelige universitet. ISSN 9788247124932. Fulltekst i vitenarkiv Vis sammendrag

  Recently, psychiatric hospitals in Norway have been criticised for premature discharges and for poor assessments of patients’ risks of violence or self-harm. Due to the high turnover of patients and the obligation to admit all acutely ill patients who are in need of hospitalisation, the acute wards are particularly exposed to such criticism. Unstructured clinical judgements alone still appear to be the dominant approach to risk assessments. Currently used instruments for risk assessment are time consuming, and their use require special expertise. The goal of the “Risk Project” at Ålesund Hospital was early identification of patients in need of risk assessments. Various screening methods were tested in a prospective, naturalistic design. This dissertation is a part of the larger Risk Project.&nbsp; In the dissertation, different approaches towards risk analyses of violence, suicide and self-injury were examined: (i) Biologically based, in which lipids and serotonin are measured in the blood; (ii) Patient based, in which patients’ self-reports of risk (SRS) are employed, and (iii) Structured professional, by applying a violence screening instrument developed for use in acute psychiatry (V-RISK-10). SRS and V-RISK-10 were scored both at the time of admittance and discharge. Blood was drawn at admission. These measures were then compared with the episodes of violent, suicidal and self-injurious behaviour recorded during the patient’s hospital stay and also, during the first year after discharge. The study sample for the biological markers and the SRSs included all of the acutely admitted patients during one year (n=489) in one acute psychiatric unit. The V-RISK-10 study included all admissions of two units (n=1017). The numbers of patients who completed the study were 254 during their hospital stay and 196 after discharge, all with regard to lipids/serotonin, 429 and 266 for SRS, and 980 and 381 for V-RISK-10, respectively. Similar to findings from other studies, low concentrations of total cholesterol were found to predict inpatient suicidal and violent behaviour and also, violent behaviour three months after discharge. Low HDL levels were predictive of violence repeaters. High triglyceride levels predicted self-injurious behaviour (SIB) during the hospital stay, and both suicidal behaviour and SIB during the first year after discharge. The best results were obtained among patients who had recorded episodes of both suicidal behaviour and SIB. This finding contradicts prior studies on self-harm but concurs with three recent studies that look at the effects of short-term and chronic psychological stress. No significant correlations between serotonin levels and violence, suicidal behaviour or SIB were found in our sample. SRS predicted violence, suicidal behaviour and SIB both during the hospital stay and at three months after discharge. In addition, SRS of violence was also significant at 12 months after discharge. The accuracy was higher for self-harm during the hospital stays and for violence after discharge. We found no other validation studies of patients’ self-reported risk of suicide or violence. The predictive validity of the V-RISK-10 was equal to or better than those of the comprehensive risk assessment instruments, and it was very high in relation to severe violence. The screening instrument was sensitive to the risk of violence independent of gender and even for patients without any known history of violence. Despite significant findings for the lipids and SRS, these methods are not recommended for regular clinical use as single predictor variables, but they may be used together in combination with established risk procedures or clinical judgements. V-RISK-10 demonstrated good psychometric properties as a violence screening tool for acute psychiatry. Further research should be undertaken to confirm the findings

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