Job strain as a risk factor for clinical depression: systematic review and meta-analysis with additional individual participant data

BACKGROUND

Adverse psychosocial working environments characterized by job strain (the combination of high demands and low control at work) are associated with an increased risk of depressive symptoms among employees, but evidence on clinically diagnosed depression is scarce. We examined job strain as a risk factor for clinical depression.

METHOD

We identified published cohort studies from a systematic literature search in PubMed and PsycNET and obtained 14 cohort studies with unpublished individual-level data from the Individual-Participant-Data Meta-analysis in Working Populations (IPD-Work) Consortium. Summary estimates of the association were obtained using random-effects models. Individual-level data analyses were based on a pre-published study protocol.

RESULTS

We included six published studies with a total of 27 461 individuals and 914 incident cases of clinical depression. From unpublished datasets we included 120 221 individuals and 982 first episodes of hospital-treated clinical depression. Job strain was associated with an increased risk of clinical depression in both published [relative risk (RR) = 1.77, 95% confidence interval (CI) 1.47-2.13] and unpublished datasets (RR = 1.27, 95% CI 1.04-1.55). Further individual participant analyses showed a similar association across sociodemographic subgroups and after excluding individuals with baseline somatic disease. The association was unchanged when excluding individuals with baseline depressive symptoms (RR = 1.25, 95% CI 0.94-1.65), but attenuated on adjustment for a continuous depressive symptoms score (RR = 1.03, 95% CI 0.81-1.32).

CONCLUSIONS

Job strain may precipitate clinical depression among employees. Future intervention studies should test whether job strain is a modifiable risk factor for depression.

Risk of depressive disorder following disasters and military deployment: systematic review with meta-analysis

BACKGROUND

Numerous studies describe the occurrence of post-traumatic stress disorder following disasters, but less is known about the risk of major depression.

AIMS

To review the risk of depressive disorder in people surviving disasters and in soldiers returning from military deployment.

METHOD

A systematic literature search combined with reference screening identified 23 controlled epidemiological studies. We used random effects models to compute pooled odds ratios (ORs).

RESULTS

The average OR was significantly elevated following all types of exposures: natural disaster OR = 2.28 (95% CI 1.30-3.98), technological disaster OR = 1.44 (95% CI 1.21-1.70), terrorist acts OR = 1.80 (95% CI 1.38-2.34) and military combat OR = 1.60 (95% CI 1.09-2.35). In a subset of ten high-quality studies OR was 1.41 (95% CI 1.06-1.87).

CONCLUSIONS

Disasters and combat experience substantially increase the risk of depression. Whether psychological trauma per se or bereavement is on the causal path is unresolved.

Job strain and the risk of severe asthma exacerbations: a meta-analysis of individual-participant data from 100 000 European men and women

Background

Many patients and healthcare professionals believe that work‐related psychosocial stress, such as job strain, can make asthma worse, but this is not corroborated by empirical evidence. We investigated the associations between job strain and the incidence of severe asthma exacerbations in working‐age European men and women.

Methods

We analysed individual‐level data, collected between 1985 and 2010, from 102 175 working‐age men and women in 11 prospective European studies. Job strain (a combination of high demands and low control at work) was self‐reported at baseline. Incident severe asthma exacerbations were ascertained from national hospitalization and death registries. Associations between job strain and asthma exacerbations were modelled using Cox regression and the study‐specific findings combined using random‐effects meta‐analyses.

Results

During a median follow‐up of 10 years, 1 109 individuals experienced a severe asthma exacerbation (430 with asthma as the primary diagnostic code). In the age‐ and sex‐adjusted analyses, job strain was associated with an increased risk of severe asthma exacerbations defined using the primary diagnostic code (hazard ratio, HR: 1.27, 95% confidence interval, CI: 1.00, 1.61). This association attenuated towards the null after adjustment for potential confounders (HR: 1.22, 95% CI: 0.96, 1.55). No association was observed in the analyses with asthma defined using any diagnostic code (HR: 1.01, 95% CI: 0.86, 1.19).

Conclusions

Our findings suggest that job strain is probably not an important risk factor for severe asthma exacerbations leading to hospitalization or death.

Job strain in relation to body mass index: pooled analysis of 160 000 adults from 13 cohort studies

BACKGROUND

Evidence of an association between job strain and obesity is inconsistent, mostly limited to small-scale studies, and does not distinguish between categories of underweight or obesity subclasses.

OBJECTIVES

To examine the association between job strain and body mass index (BMI) in a large adult population.

METHODS

We performed a pooled cross-sectional analysis based on individual-level data from 13 European studies resulting in a total of 161 746 participants (49% men, mean age, 43.7 years). Longitudinal analysis with a median follow-up of 4 years was possible for four cohort studies (n = 42 222).

RESULTS

A total of 86 429 participants were of normal weight (BMI 18.5-24.9 kg m(-2) ), 2149 were underweight (BMI < 18.5 kg m(-2) ), 56 572 overweight (BMI 25.0-29.9 kg m(-2) ) and 13 523 class I (BMI 30-34.9 kg m(-2) ) and 3073 classes II/III (BMI ≥ 35 kg m(-2) ) obese. In addition, 27 010 (17%) participants reported job strain. In cross-sectional analyses, we found increased odds of job strain amongst underweight [odds ratio 1.12, 95% confidence interval (CI) 1.00-1.25], obese class I (odds ratio 1.07, 95% CI 1.02-1.12) and obese classes II/III participants (odds ratio 1.14, 95% CI 1.01-1.28) as compared with participants of normal weight. In longitudinal analysis, both weight gain and weight loss were related to the onset of job strain during follow-up.

CONCLUSIONS

In an analysis of European data, we found both weight gain and weight loss to be associated with the onset of job strain, consistent with a 'U'-shaped cross-sectional association between job strain and BMI. These associations were relatively modest; therefore, it is unlikely that intervention to reduce job strain would be effective in combating obesity at a population level.

Burnout as a predictor of self-reported sickness absence among human service workers: prospective findings from three year follow up of the PUMA study

AIM

To investigate whether burnout predicts sickness absence days and sickness absence spells in human service workers.

METHOD

A total of 824 participants from an ongoing prospective study in different human service sector organisations were eligible for the three year follow up analysis. Burnout was measured with the work related burnout scale of the Copenhagen Burnout Inventory. Sickness absence was measured with self-reported number of days and spells during the last 12 months before the baseline and the follow up survey. A Poisson regression model with a scale parameter was used to account for over dispersion. A linear regression model was used for analysing changes in burnout and absence between baseline and follow up.

RESULTS

Burnout was prospectively associated with both sickness absence days and sickness absence spells per year. Differences in sickness absence days varied from a mean of 5.4 days per year in the lowest quartile of the work related burnout scale to a mean of 13.6 in the highest quartile. An increase of one standard deviation on the work related burnout scale predicted an increase of 21% in sickness absence days per year (rate ratio 1.21, 95% CI 1.11 to 1.32) after adjusting for gender, age, organisation, socioeconomic status, lifestyle factors, family status, having children under 7 years of age, and prevalence of diseases. Regarding sickness absence spells, an increase of one standard deviation on the work related burnout scale predicted an increase of 9% per year (rate ratio 1.09, 95% CI 1.02 to 1.17). Changes in burnout level from baseline to follow up were positively associated with changes in sickness absence days (estimate 1.94 days/year, SE 0.63) and sickness absence spell (estimate 0.34 spells/year, SE 0.08).

CONCLUSION

The findings indicate that burnout predicts sickness absence. Reducing burnout is likely to reduce sickness absence.

Life expectancies for individuals with psychiatric diagnoses

The aim of the study was to estimate life expectancies in different diagnostic groups for individuals treated as inpatients at Swedish psychiatric clinics. All individuals, older than 18 y and alive on the first of January 1983, who had been registered in the National Hospital Discharge Registry by a psychiatric clinic in 1978-82, were monitored for mortality during 1983 by using the National Cause of Death Registry. The study group consisted of 91 385 men and 77 217 women. The patients were divided into nine diagnostic groups according to the principal diagnosis registered at the latest discharge. Actuarial mathematics was used to construct life expectancy tables, which present the number of years expected to live, by gender and diagnostic group. Expectancies of life were significantly shortened for both genders and in all nine diagnostic groups (with one exception). Mental disorders in general are life shortening. This fact should be recognised in community health when setting health priorities. It should also be addressed in curricula as well as in treatment and preventive programmes.