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Aim: This study examines the association between musculoskeletal complaints and subsequent use of antidepressants and/or psychiatric hospital treatment for depressive mood disorders in the Danish labour force. Methods: The study is based on two cohorts. The first cohort is the total labour force in 21 Danish municipalities (n =693,860), where the risk of depression (psychiatric diagnosis or antidepressant treatment) during 2010–2015 was compared between individuals on long-term sickness absence due to musculoskeletal disorders (MSD) and non-sick-listed gainfully employed individuals. The second cohort is a random sample of the Danish labour force (n =9248) who were followed during 2011–2015 to estimate the association between self-rated musculoskeletal pain and depression. All analyses were controlled for age, sex, calendar period and socio-economic status. Results: Compared to non-sick-listed gainfully employed individuals, there was an increased risk of depression in individuals sick-listed with MSD, with rate ratios of 2.39 (99% confidence interval (CI) 2.22–2.58) for individuals with less severe MSD and 4.27 (99% CI 3.98–4.59) for individuals with more severe MSD. There was also an increased risk of depression associated with self-rated pain (yes vs. no), with a rate ratio of 2.17 (99% CI 1.69–2.78). The population attributable fraction of depression from musculoskeletal pain was 0.35 (99% CI 0.24–0.45). Conclusions: The results of the present study indicate that musculoskeletal pain is an important predictor of indicators of depression in the general working population of Denmark. [ABSTRACT FROM AUTHOR]

OBJECTIVE: This study aimed to investigate the possibility of a prospective association between long working hours and use of psychotropic medicine. METHODS: Survey data drawn from random samples of the general working population of Denmark in the time period 1995–2010 were linked to national registers covering all inhabitants. The participants were followed for first occurrence of redeemed prescriptions for psychotropic medicine. The primary analysis included 25 959 observations (19 259 persons) and yielded a total of 2914 new cases of psychotropic drug use in 99 018 person-years at risk. Poisson regression was used to model incidence rates of redeemed prescriptions for psychotropic medicine as a function of working hours (32–40, 41–48, >48 hours/week). The analysis was controlled for gender, age, sample, shift work, and socioeconomic status. A likelihood ratio test was used to test the null hypothesis, which stated that the incidence rates were independent of weekly working hours. RESULTS: The likelihood ratio test did not reject the null hypothesis (P=0.085). The rate ratio (RR) was 1.04 [95% confidence interval (95% CI) 0.94–1.15] for the contrast 41–48 versus 32–40 work hours/week and 1.15 (95% CI 1.02–1.30) for >48 versus 32–40 hours/week. None of the rate ratios that were estimated in the present study were statistically significant after adjustment for multiple testing. However, stratified analyses, in which 30 RR were estimated, generated the hypothesis that overtime work (>48 hours/week) might be associated with an increased risk among night or shift workers (RR=1.51, 95% CI 1.15–1.98). CONCLUSION: The present study did not find a statistically significant association between long working hours and incidence of psychotropic drug usage among Danish employees.

Aims: A systematic review and meta-analysis have found that long working hours were prospectively associated with an increased risk of overall stroke. The primary aim of the present study was to test if this finding could be reproduced in a sample that has been randomly selected from the general workforce of Denmark. A secondary aim was to estimate the association for haemorrhagic and ischaemic stroke separately. Methods: Individual participant data on 20- to 64-year-old employees were drawn from the Danish Labour Force survey, 1999-2013, and linked to data on socio-economic status (sEs), migrations, hospitalisations and deaths from national registers. The participants were followed from the time of the interview until the end of 2014. Poisson regression was used to estimate age-, sex- and sEs-adjusted rate ratios for stroke as a function of weekly working hours. Results: With 35-40 working hours per week as reference, the estimated rate ratios for overall stroke were 0.97 (95% confidence interval (CI) 0.83-1.13) for 41-48 working hours, 1.10 (95% CI 0.86-1.39) for 49-54 working hours and 0.89 (95% CI 0.69-1.16) for ≥55 working hours. The estimated rate ratios per one category increase in working hours were 0.99 (95% CI 0.93--1.06) for overall stroke, 0.96 (95% CI 0.88--1.05) for ischaemic stroke and 1.15 (95% CI 1.02--1.31) for haemorrhagic stroke. Conclusions: Our analysis does not support the hypothesis that long working hours are associated with increased rates of overall stroke. It suggests, however, that long working hours might be associated with increased rates of haemorrhagic stroke. [ABSTRACT FROM AUTHOR]

Zirconia as a restoration dental material are gaining attention because of their high mechanical properties and good biocompatibility. Therefore, investigation of the flexural strength of zirconia is of great interest. For this purpose, Weibull statistics for description of the material reliability are frequently used. The aim of this work was to present a blinded data set to two independent statisticians for two parallel statistical analyses in order to find an optimal statistical approach for analysis of in-vitro measured flexural strength data of zirconia materials. A prospectively planned independent blinded statistical analysis implementing three quality control actions “blinded data set”, “independent statistical analyses” and “parallel manuscript writing” was designed. Statistical analysis paths taken by both biostatisticians differed. They arrived at complementary results. The major difference was caused by two alternative distributional assumptions (Weibull/Normal) and alternative fitting methods (LS/ML). The parallel statistical analysis and manuscript writing approach on a blinded data set greatly supported our choice of statistical methods for analysis of flexural strength results of zirconia materials. [ABSTRACT FROM AUTHOR]

Objective This study aimed to investigate the possibility of a prospective association between long working hours and use of psychotropic medicine. Methods Survey data drawn from random samples of the general working population of Denmark in the time period 1995-2010 were linked to national registers covering all inhabitants. The participants were followed for first occurrence of redeemed prescriptions for psychotropic medicine. The primary analysis included 25 959 observations (19 259 persons) and yielded a total of 2914 new cases of psychotropic drug use in 99 018 person-years at risk. Poisson regression was used to model incidence rates of redeemed prescriptions for psychotropic medicine as a function of working hours (32-40, 41-48, >48 hours/week). The analysis was controlled for gender, age, sample, shift work, and socioeconomic status. A likelihood ratio test was used to test the null hypothesis, which stated that the incidence rates were independent of weekly working hours. Results The likelihood ratio test did not reject the null hypothesis (P=0.085). The rate ratio (RR) was 1.04 [95% confidence interval (95% CI) 0.94-1.15] for the contrast 41-48 versus 32-40 work hours/week and 1.15 (95% CI 1.02-1.30) for >48 versus 32-40 hours/week. None of the rate ratios that were estimated in the present study were statistically significant after adjustment for multiple testing. However, stratified analyses, in which 30 RR were estimated, generated the hypothesis that overtime work (>48 hours/week) might be associated with an increased risk among night or shift workers (RR=1.51, 95% CI 1.15-1.98). Conclusion The present study did not find a statistically significant association between long working hours and incidence of psychotropic drug usage among Danish employees. [ABSTRACT FROM AUTHOR]