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Many clinicians, patients and patient advocacy groups believe stress to have a causal role in inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis. However, this is not corroborated by clear epidemiological research evidence. We investigated the association between work-related stress and incident Crohn's disease and ulcerative colitis using individual-level data from 95,000 European adults.We conducted individual-participant data meta-analyses in a set of pooled data from 11 prospective European studies. All studies are a part of the IPD-Work Consortium. Work-related psychosocial stress was operationalised as job strain (a combination of high demands and low control at work) and was self-reported at baseline. Crohn's disease and ulcerative colitis were ascertained from national hospitalisation and drug reimbursement registers. The associations between job strain and inflammatory bowel disease outcomes were modelled using Cox proportional hazards regression. The study-specific results were combined in random effects meta-analyses.Of the 95,379 participants who were free of inflammatory bowel disease at baseline, 111 men and women developed Crohn's disease and 414 developed ulcerative colitis during follow-up. Job strain at baseline was not associated with incident Crohn's disease (multivariable-adjusted random effects hazard ratio: 0.83, 95% confidence interval: 0.48, 1.43) or ulcerative colitis (hazard ratio: 1.06, 95% CI: 0.76, 1.48). There was negligible heterogeneity among the study-specific associations.Our findings suggest that job strain, an indicator of work-related stress, is not a major risk factor for Crohn's disease or ulcerative colitis.

The relationship between work-related stress and alcohol intake is uncertain. In order to add to the thus far inconsistent evidence from relatively small studies, we conducted individual-participant meta-analyses of the association between work-related stress (operationalised as self-reported job strain) and alcohol intake.We analysed cross-sectional data from 12 European studies (n = 142 140) and longitudinal data from four studies (n = 48 646). Job strain and alcohol intake were self-reported. Job strain was analysed as a binary variable (strain vs. no strain). Alcohol intake was harmonised into the following categories: none, moderate (women: 1-14, men: 1-21 drinks/week), intermediate (women: 15-20, men: 22-27 drinks/week) and heavy (women: >20, men: >27 drinks/week). Cross-sectional associations were modelled using logistic regression and the results pooled in random effects meta-analyses. Longitudinal associations were examined using mixed effects logistic and modified Poisson regression. Compared to moderate drinkers, non-drinkers and (random effects odds ratio (OR): 1.10, 95% CI: 1.05, 1.14) and heavy drinkers (OR: 1.12, 95% CI: 1.00, 1.26) had higher odds of job strain. Intermediate drinkers, on the other hand, had lower odds of job strain (OR: 0.92, 95% CI: 0.86, 0.99). We found no clear evidence for longitudinal associations between job strain and alcohol intake.Our findings suggest that compared to moderate drinkers, non-drinkers and heavy drinkers are more likely and intermediate drinkers less likely to report work-related stress.

Tobacco smoking is a major contributor to the public health burden and healthcare costs worldwide, but the determinants of smoking behaviours are poorly understood. We conducted a large individual-participant meta-analysis to examine the extent to which work-related stress, operationalised as job strain, is associated with tobacco smoking in working adults.We analysed cross-sectional data from 15 European studies comprising 166,130 participants. Longitudinal data from six studies were used. Job strain and smoking were self-reported. Smoking was harmonised into three categories never, ex- and current. We modelled the cross-sectional associations using logistic regression and the results pooled in random effects meta-analyses. Mixed effects logistic regression was used to examine longitudinal associations. Of the 166,130 participants, 17% reported job strain, 42% were never smokers, 33% ex-smokers and 25% current smokers. In the analyses of the cross-sectional data, current smokers had higher odds of job strain than never-smokers (age, sex and socioeconomic position-adjusted odds ratio: 1.11, 95% confidence interval: 1.03, 1.18). Current smokers with job strain smoked, on average, three cigarettes per week more than current smokers without job strain. In the analyses of longitudinal data (1 to 9 years of follow-up), there was no clear evidence for longitudinal associations between job strain and taking up or quitting smoking.Our findings show that smokers are slightly more likely than non-smokers to report work-related stress. In addition, smokers who reported work stress smoked, on average, slightly more cigarettes than stress-free smokers.

Rationale & Objective: Using OVERTURE (NCT01430494) study data on patient-perceived health, health care utilization, and productivity in autosomal dominant polycystic kidney disease (ADPKD), this research was conducted to characterize the burden of illness in patients with ADPKD and assess whether patient-reported outcome (PRO) assessment scores predict clinical and health-economic outcomes. Study Design: Data were analyzed from a prospective, observational study. Setting & Participants: The study cohort comprised 3,409 individuals with ADPKD in 20 countries who were aged 12-78 years and were in chronic kidney disease (CKD) stages G1-G5 and Mayo risk subclasses 1A-1E. Predictors: Scores on PRO instruments, including disease-specific assessments [ADPKD-Impact Scale (ADPKD-IS), and ADPKD-Urinary Impact Scale (ADPKD-UIS)] and generic measures were assessed. Outcomes: Clinical variables [eg, height-adjusted total kidney volume (htTKV), estimated glomerular filtration rate (eGFR), and abdominal girth] and health-economic outcomes were assessed. Analytical Approach: Associations among variables were evaluated using Spearman correlations, logistic regression, and generalized linear mixed effects repeated measures models. Results: Baseline CKD stage and Mayo risk classification showed little correlation with baseline PRO scores; however, scores on disease-specific instruments and measures of physical functioning were worse at more severe CKD stages. PRO scores predicted hospitalizations and sick days at 6-18 months, with strongest associations noted for the ADPKD-IS. PRO scores were not associated with htTKV and eGFR, but worse PRO scores were associated with greater abdominal girth. Poor baseline ADPKD-IS scores were positively associated with occurrence of ADPKD-related symptoms up to 18 months, including kidney pain (OR, 5.30; 95% CI, 2.75-10.24), hematuria (OR, 4.58; 95% CI, 1.99-10.53), and urinary tract infection (OR, 4.41; 95% CI, 1.93-10.11; P

Background: Previous studies have shown that gainfully employed individuals with high work demands and low control at work (denoted “job strain”) are at increased risk of common mental disorders, including depression. Most existing studies have, however, measured depression using self-rated symptom scales that do not necessarily correspond to clinically diagnosed depression. In addition, a meta-analysis from 2008 indicated publication bias in the field. Methods: This study protocol describes the planned design and analyses of an individual participant data meta-analysis, to examine whether job strain is associated with an increased risk of clinically diagnosed unipolar depression based on hospital treatment registers. The study will be based on data from approximately 120,000 individuals who participated in 14 studies on work environment and health in 4 European countries. The self-reported working conditions data will be merged with national registers on psychiatric hospital treatment, primarily hospital admissions. Study-specific risk estimates for the association between job strain and depression will be calculated using Cox regressions. The study-specific risk estimates will be pooled using random effects meta-analysis. Discussion: The planned analyses will help clarify whether job strain is associated with an increased risk of clinically diagnosed unipolar depression. As the analysis is based on pre-planned study protocols and an individual participant data meta-analysis, the pooled risk estimates will not be influenced by selective reporting and publication bias. However, the results of the planned study may only pertain to severe cases of unipolar depression, because of the outcome measure applied.

Background: Previous studies have shown that gainfully employed individuals with high work demands and low control at work (denoted “job strain”) are at increased risk of common mental disorders, including depression. Most existing studies have, however, measured depression using self-rated symptom scales that do not necessarily correspond to clinically diagnosed depression. In addition, a meta-analysis from 2008 indicated publication bias in the field. Methods: This study protocol describes the planned design and analyses of an individual participant data meta-analysis, to examine whether job strain is associated with an increased risk of clinically diagnosed unipolar depression based on hospital treatment registers. The study will be based on data from approximately 120,000 individuals who participated in 14 studies on work environment and health in 4 European countries. The self-reported working conditions data will be merged with national registers on psychiatric hospital treatment, primarily hospital admissions. Study-specific risk estimates for the association between job strain and depression will be calculated using Cox regressions. The study-specific risk estimates will be pooled using random effects meta-analysis. Discussion: The planned analyses will help clarify whether job strain is associated with an increased risk of clinically diagnosed unipolar depression. As the analysis is based on pre-planned study protocols and an individual participant data meta-analysis, the pooled risk estimates will not be influenced by selective reporting and publication bias. However, the results of the planned study may only pertain to severe cases of unipolar depression, because of the outcome measure applied.

OBJECTIVES: This study aimed to (i) estimate working life expectancies (WLE) and the number of working years lost (WYL) among individuals with type 1 and type 2 diabetes over a 30-year period and (ii) identify educational differences in WLE and WYL. METHODS: Individuals aged 18–65 years diagnosed with type 1 (N=33 188) or type 2 diabetes (N=81 930) in 2000–2016 and age- and gender-matched controls without diabetes (N=663 656) were identified in Danish national registers. WLE in years were estimated as time in employment from age 35–65 years. We used a life-table approach with multi-state (eg, disability pension, sickness absence, unemployment) Cox proportional hazard modeling. Analyses were performed separately for sex, cohabitation status, educational duration, and type of diabetes. Inverse probability weights accounted for differences between populations. RESULTS: People with diabetes had significantly shorter WLE and greater WYL compared to people without diabetes over the 30-year span. At age 35, cohabitant women with lower education and diabetes lost up to 8.0 years [95% confidence interval (CI) 5.0–11.0] and men 7.0 years (95% CI 4.0–8.7). WYL among women with higher education was 4.4 (95% CI 6.6–2.3) and 3.7 years among men (95% CI 1.5–4.5). Compared to people with type 2 diabetes, those with type 1 spend significantly more years in disability pension, but there were no significant differences in the other WYL estimates. CONCLUSIONS: The WYL among people with diabetes is substantial and characterized by social disparities. The WYL help identify intervention targets at different ages, types of diabetes, sex, educational and cohabitant status.

Objective: To propose the minimally important difference (MID) for the SF-36 Vitality (VT) scale by evaluating the association of score differences with clinical conditions and functional outcomes.Methods: Analyses were performed on data from the Medical Outcomes Study (n = 3445). The first analyses regressed VT scores (0–100 scale) on chronic conditions that cause fatigue in order to determine the impact of each condition on VT. The second set of analyses examined the relationship between baseline VT scores and other outcomes at baseline, 1-year, and 7-year follow-up.Results: VT scores were significantly reduced in patients with anemia [5 points (95% CI 2–9 points)], CHF [6 (3–9) points], and COPD [6 (3–9) points]. Decreases in VT score were significantly associated with increased odds of negative outcomes, including inability to work due to health at baseline [OR (5 points) = 1.27 (95% CI 1.24–1.31), OR (10 points) = 1.62 (1.54–1.71)], job loss at 1 year [OR (5) = 1.13 (1.08–1.19), OR (10) = 1.28 (1.17–1.41)], hospitalization at 1 year [OR (5) = 1.08 (1.05–1.11), OR (10) = 1.17 (1.10–1.23)], short-term mortality [0–18 months–Hazard Ratio (HR) (5) = 1.10–1.71, HR (10) = 1.21–2.39, depending on VT level] and long-term mortality [19+ months–HR (5) = 1.05–1.31, HR (10) = 1.10–1.54]. The mortality risk increase was largest at low VT levels.Conclusions: VT decrements of 5–10 points were seen for diseases known to cause fatigue. Further, differences of 5–10 points in the VT score were associated with significant increased risk of negative outcomes. We recommend an MID of 5 points for analyses of groups with VT scores below average. For follow-up of individual patients, we recommend a 10-point difference as important. [ABSTRACT FROM AUTHOR]

Abstract Background The SF-6Dv2 classification system assesses health states in six domains—physical functioning, role function, bodily pain, vitality, social functioning, and mental health. Scores have previously been derived from the SF-36v2® Health Survey. We aimed to develop a six-item stand-alone SF-6Dv2 Health Utility Survey (SF-6Dv2 HUS) and evaluate its comprehensibility. Methods Two forms of a stand-alone SF-6Dv2 HUS were developed for evaluation. Form A had 6 questions with 5–6 response choices, while Form B used 6 headings and 5–6 statements describing the health levels within each domain. The two forms were evaluated by 40 participants, recruited from the general population. Participants were randomized to debrief one form of the stand-alone SF-6Dv2 HUS during a 75-min interview, using think-aloud techniques followed by an interviewer-led detailed review. Participants then reviewed the other form of SF-6Dv2 and determined which they preferred. Any issues or confusion with items was recorded, as was as overall preference. Data were analyzed using Microsoft Excel and NVivo Software (v12). Results Participants were able to easily complete both forms. Participant feedback supported the comprehensibility of the SF-6Dv2 HUS. When comparing forms, 25/40 participants preferred Form A, finding it clearer and easier to answer when presented in question/response format. The numbered questions and underlining of key words in Form A fostered quick and easy comprehension and completion of the survey. However, despite an overall preference for Form A, almost half of participants (n = 19) preferred the physical functioning item in Form B, with more descriptive response choices. Conclusion The results support using Form A, with modifications to the physical functioning item, as the stand-alone SF-6Dv2 HUS. The stand-alone SF-6Dv2 HUS is brief, easy to administer, and comprehensible to the general population.

Abstract Background The 12-item Medical Outcomes Study Sleep Scale (MOS Sleep Scale) has been used to capture patient-reported sleep problems in hundreds of studies. A revised version of the MOS Sleep Scale (MOS Sleep-R) was developed that uses simplified response sets, provides interpretable norm-based scoring, and has two recall versions (one-week or four-week). The objective of this study was to evaluate the psychometric properties (reliability and construct validity) of the MOS Sleep-R using data from a representative sample of U.S. adults. Methods Standardization of raw scores into norm-based T-scores (mean = 50, standard deviation = 10) was based on data from a 2009 U.S. internet-based general population survey. The internal consistency reliability of multi-item subscales and global sleep problems indices for both one-week and four-week recall forms of the MOS Sleep-R were examined using Cronbach’s alphas and inter-item correlations. Construct validity was tested by comparing item-scale correlations between items within subscales with item-scale correlations across subscales. Scale-level convergent validity was tested using correlations with measures including generic health-related quality of life (i.e., SF-36v2) and other relevant outcomes (e.g., job performance, number of days in bed due to illness or injury, happiness/satisfaction with life, frequency of stress/pressure in daily life, the impact of stress/pressure on health, and overall health). Results The one-week and four-week recall forms of the MOS Sleep-R were completed by 2045 and 2033 respondents, respectively. The psychometric properties of the one-week and four-week forms were similar. All multi-item subscales and global index scores showed adequate internal consistency reliability (all Cronbach’s alpha > 0.75). Patterns of inter-item and item-scale correlations support the scaling assumptions of the MOS Sleep-R. Patterns of correlations between MOS Sleep-R scores with criterion measures of health-related quality of life and other outcomes indicated adequate construct validity. Conclusions The MOS Sleep-R introduces a number of revisions to the original survey, including simplified response sets, the introduction of a one-week recall form, and norm-based scoring that enhances interpretability of scores. Both the one-week and four-week recall period forms of the MOS Sleep-R demonstrated good internal consistency reliability and construct validity in a U.S. general population sample.

Summary: Background: Heavy alcohol consumption increases the risk of several chronic diseases. In this multicohort study, we estimated the number of life-years without major chronic diseases according to different characteristics of alcohol use. Methods: In primary analysis, we pooled individual-level data from up to 129,942 adults across 12 cohort studies with baseline data collection on alcohol consumption, drinking patterns, and history between 1986 and 2005 (the IPD-Work Consortium). Self-reported alcohol consumption was categorised according to UK guidelines – non-drinking (never or former drinkers); moderate consumption (1–14 units); heavy consumption (>14 units per week). We further subdivided moderate and heavy drinkers by binge drinking pattern (alcohol-induced loss of consciousness). In addition, we assessed problem drinking using linked data on hospitalisations due to alcohol abuse or poisoning. Follow-up for chronic diseases for all participants included incident type 2 diabetes, coronary heart disease, stroke, cancer, and respiratory disease (asthma and chronic obstructive pulmonary disease) as ascertained via linkage to national morbidity and mortality registries, repeated medical examinations, and/or self-report. We estimated years lived without any of these diseases between 40 and 75 years of age according to sex and characteristics of alcohol use. We repeated the main analyses using data from 427,621 participants in the UK Biobank cohort study. Findings: During 1·73 million person-years at risk, 22,676 participants in IPD-Work cohorts developed at least one chronic condition. From age 40 to 75 years, never-drinkers [men: 29·3 (95%CI 27·9–30·8) years, women 29·8 (29·2–30·4) years)] and moderate drinkers with no binge drinking habit [men 28·7 (28·4–29·0) years, women 29·6 (29·4–29·7) years] had the longest disease-free life span. A much shorter disease-free life span was apparent in participants who experienced alcohol poisoning [men 23·4 (20·9–26·0) years, women 24·0 (21·4–26·5) years] and those with self-reported heavy overall consumption and binge drinking [men: 26·0 (25·3–26·8), women 27·5 (26·4–28·5) years]. The pattern of results for alcohol poisoning and self-reported alcohol consumption was similar in UK Biobank. In IPD-Work and UK Biobank, differences in disease-free years between self-reported moderate drinkers and heavy drinkers were 1·5 years or less. Interpretation: Individuals with alcohol poisonings or heavy self-reported overall consumption combined with a binge drinking habit have a marked 3- to 6-year loss in healthy longevity. Differences in disease-free life between categories of self-reported weekly alcohol consumption were smaller. Funding: Medical Research Council, National Institute on Aging, NordForsk, Academy of Finland, Finnish Work Environment Fund.

SUMMARY: Background: Studies on the association between long working hours and health have captured only a narrow range of outcomes (mainly cardiometabolic diseases and depression) and no outcome-wide studies on this topic are available. To achieve wider scope of potential harm, we examined long working hours as a risk factor for a wide range of disease and mortality endpoints. Methods: The data of this multicohort study were from two population cohorts from Finland (primary analysis, n=59 599) and nine cohorts (replication analysis, n=44 262) from Sweden, Denmark, and the UK, all part of the Individual-participant Meta-analysis in Working Populations (IPD-Work) consortium. Baseline-assessed long working hours (≥55 hours per week) were compared to standard working hours (35-40 h). Outcome measures with follow-up until age 65 years were 46 diseases that required hospital treatment or continuous pharmacotherapy, all-cause, and three cause-specific mortality endpoints, ascertained via linkage to national health and mortality registers. Findings: 2747 (4·6%) participants in the primary cohorts and 3027 (6·8%) in the replication cohorts worked long hours. After adjustment for age, sex, and socioeconomic status, working long hours was associated with increased risk of cardiovascular death (hazard ratio 1·68; 95% confidence interval 1·08-2·61 in primary analysis and 1·52; 0·90-2·58 in replication analysis), infections (1·37; 1·13-1·67 and 1·45; 1·13-1·87), diabetes (1·18; 1·01-1·38 and 1·41; 0·98-2·02), injuries (1·22; 1·00-1·50 and 1·18; 0·98-1·18) and musculoskeletal disorders (1·15; 1·06-1·26 and 1·13; 1·00-1·27). Working long hours was not associated with all-cause mortality. Interpretation: Follow-up of 50 health outcomes in four European countries suggests that working long hours is associated with an elevated risk of early cardiovascular death and hospital-treated infections before age 65. Associations, albeit weak, were also observed with diabetes, musculoskeletal disorders and injuries. In these data working long hours was not related to elevated overall mortality. Funding: NordForsk, the Medical Research Council, the National Institute on Aging, the Wellcome Trust, Academy of Finland, and Finnish Work Environment Fund.

Abstract Background Between 1975 and 1985 a total of 91 Danish patients with moderate and severe hemophilia (PWH) was infected with HIV constituting a major scandal in the Danish health care system. This study describes the burden of HIV infection among Danish PWH by evaluating changes from 1988 to 2012 in well-being, social function, experiencing stigma and openness about disease among Danish HIV+ PWH. Methods Three anonymous surveys were conducted in 1988, 2001 and 2012 targeting all Danish patients with moderate to severe hemophilia. Survey responses were received from 53, 21 and 18 HIV+ PWH respectively. A matched comparison sample of HIV− PWH was identified for each survey-year, using propensity score matching. Differences for each survey-year and trends over time were analyzed using ordinal logistic regression. Results In 1988, HIV+ PWH had more psychosomatic symptoms than HIV− PWH, but in 2001 life satisfaction was higher among HIV+ PWH than among HIV− PWH. Tests of differences in trend over time showed larger improvements in life satisfaction among HIV+ PWH than HIV− PWH, while HIV− PWH showed an increase in educational level compared to HIV+ PWH. Analysis restricted to HIV+ PWH showed an increase in perceived stigmatization. Conclusions Differences between Danish HIV+ and HIV− PWH regarding well-being and psychosomatic symptoms seem to have evened out between 1988 and 2012. However, results suggest that HIV+ PWH still experience stigmatization and lower levels of education.

Abstract Background Psychometric analyses of patient reported outcomes typically use either classical test theory (CTT), item response theory (IRT), or Rasch measurement theory (RTM). The three papers from the ISOQOL Psychometrics SIG examined the same data set using the tree different approaches. By comparing the results from these papers, the current paper aims to examine the extent to which conclusions about the validity and reliability of a PRO tool depends on the selected psychometric approach. Main text Regarding the basic statistical model, IRT and RTM are relatively similar but differ notably from CTT. However, modern applications of CTT diminish these differences. In analyses of item discrimination, CTT and IRT gave very similar results, while RTM requires equal discrimination and therefore suggested exclusion of items deviating too much from this requirement. Thus, fewer items fitted the Rasch model. In analyses of item thresholds (difficulty), IRT and RMT provided fairly similar results. Item thresholds are typically not evaluated in CTT. Analyses of local dependence showed only moderate agreement between methods, partly due to different thresholds for important local dependence. Analyses of differential item function (DIF) showed good agreement between IRT and RMT. Agreement might be further improved by adjusting the thresholds for important DIF. Analyses of measurement precision across the score range showed high agreement between IRT and RMT methods. CTT assumes constant measurement precision throughout the score range and thus gave different results. Category orderings were examined in RMT analyses by checking for reversed thresholds. However, this approach is controversial within the RMT society. The same issue can be examined by the nominal categories IRT model. Conclusions While there are well-known differences between CTT, IRT and RMT, the comparison between three actual analyses revealed a great deal of agreement between the results from the methods. If the undogmatic attitude of the three current papers is maintained, the field will be well served.

Objective/background: Associations between exposure to effort-reward imbalance at work (eg, high time pressure/low appreciation) and risk of sleep disturbances have been reported, but the direction of the effect is unclear. The present study investigated changes in effort-reward imbalance and risk of concomitant and subsequent onset of sleep disturbances. Methods: Participants with sleep disturbances at baseline were excluded. We included participants from a population-based cohort in Denmark (n = 8,464, 53.6% women, mean age = 46.6 years), with three repeated measurements (2012 (T0); 2014 (T1); 2016 (T2)). Changes in effort-reward imbalance (T0-T1) were categorized into ‘increase’, ‘decrease’ and ‘no change’. Self-reported sleep disturbances (difficulties initiating or maintaining sleep, non-restorative sleep, daytime tiredness) were dichotomized (presence versus absence). We regressed concomitant (T1) and subsequent (T2) sleep disturbances on changes in effort-reward imbalance (T0-T1) and calculated odds ratios (OR) and 95% confidence intervals, adjusted for sex, age, education and cohabitation. Results: At follow-up, 8.4% (T1) and 12.5% (T2) reported onset of sleep disturbances. Increased effort-reward imbalance was associated with concomitant sleep disturbances (T1) (OR = 3.16, 2.56–3.81), whereas decreased effort-reward imbalance was not (OR = 1.22, 0.91–1.63). There was no association between increased effort-reward imbalance and subsequent sleep disturbances (T2) (OR = 1.00, 0.74–1.37). Results were similar for men and women. Conclusions: Increased effort-reward imbalance was associated with a three-fold higher risk of concomitant onset of sleep disturbances at two-year follow-up, but not subsequent onset of sleep disturbances at four-year follow-up, indicating that changes in effort-reward imbalance have immediate rather than delayed effects on sleep impairment. It is possible that the results from the two-year follow-up were to some extent affected by reverse causality.

Background: Previous studies have shown that gainfully employed individuals with high work demands and low control at work (denoted “job strain”) are at increased risk of common mental disorders, including depression. Most existing studies have, however, measured depression using self-rated symptom scales that do not necessarily correspond to clinically diagnosed depression. In addition, a meta-analysis from 2008 indicated publication bias in the field. Methods: This study protocol describes the planned design and analyses of an individual participant data meta-analysis, to examine whether job strain is associated with an increased risk of clinically diagnosed unipolar depression based on hospital treatment registers. The study will be based on data from approximately 120,000 individuals who participated in 14 studies on work environment and health in 4 European countries. The self-reported working conditions data will be merged with national registers on psychiatric hospital treatment, primarily hospital admissions. Study-specific risk estimates for the association between job strain and depression will be calculated using Cox regressions. The study-specific risk estimates will be pooled using random effects meta-analysis. Discussion: The planned analyses will help clarify whether job strain is associated with an increased risk of clinically diagnosed unipolar depression. As the analysis is based on pre-planned study protocols and an individual participant data meta-analysis, the pooled risk estimates will not be influenced by selective reporting and publication bias. However, the results of the planned study may only pertain to severe cases of unipolar depression, because of the outcome measure applied.

Background: Previous studies have shown that gainfully employed individuals with high work demands and low control at work (denoted “job strain”) are at increased risk of common mental disorders, including depression. Most existing studies have, however, measured depression using self-rated symptom scales that do not necessarily correspond to clinically diagnosed depression. In addition, a meta-analysis from 2008 indicated publication bias in the field. Methods: This study protocol describes the planned design and analyses of an individual participant data meta-analysis, to examine whether job strain is associated with an increased risk of clinically diagnosed unipolar depression based on hospital treatment registers. The study will be based on data from approximately 120,000 individuals who participated in 14 studies on work environment and health in 4 European countries. The self-reported working conditions data will be merged with national registers on psychiatric hospital treatment, primarily hospital admissions. Study-specific risk estimates for the association between job strain and depression will be calculated using Cox regressions. The study-specific risk estimates will be pooled using random effects meta-analysis. Discussion: The planned analyses will help clarify whether job strain is associated with an increased risk of clinically diagnosed unipolar depression. As the analysis is based on pre-planned study protocols and an individual participant data meta-analysis, the pooled risk estimates will not be influenced by selective reporting and publication bias. However, the results of the planned study may only pertain to severe cases of unipolar depression, because of the outcome measure applied.