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.
Methods We identified published cohort studies from a systematic literature search in
PubMed and PsycNET and obtained 14 cohort studies with unpublished individuallevel
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 (F1000Res 2013;2:233).
Results We included 6 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 From unpublished datasets we included 120 221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[RR]= 1.77, 95% confidence interval [CI] 1.47-2.13) and unpublished datasets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).
Conclusion Job strain may precipitate clinical depression among employees. Future
intervention studies