Background: Work stress is a recognized risk factor for mental health disorders, but it is not known whether work stress is associated with the morbidity among individuals with psychologic distress. Another shortcoming in earlier research is related to common method bias-the use of individual perceptions of both work stress and psychologic distress. This prospective study was assessed using the General Health Questionnaire (GHQ-12), which identified psychologic distress as a predictor of sickness absence and the effect of work-unit measures of job strain on sickness absence among cases.
Methods: Survey data were collected on work stress, indicated by high job strain, for a cohort of public sector employees (6,663 women, 1,323 men), aged 18 to 62 at baseline in 2000-2002, identified as GHQ-12 cases. Coworker assessments of job strain were used to control for bias due to response style. A 2-year follow-up included recorded long-term (>7 days) medically certified sickness absence. Adjustments were made for age, socioeconomic position, baseline chronic physical disease, smoking, and heavy alcohol consumption.
Results: Cases with psychologic distress had 1.3 to 1.4 times higher incidence of long-term sickness absence than non cases. Among cases, high job strain predicted sickness absence (hazard ratio 1.17 in women, 1.41 in men). The significant effect of job strain on sickness absence was found among workers in high socioeconomic positions (hazard ratio 1.54 for women, 1.58 for men) but not among employees in low socioeconomic positions (hazard ratio 1.06 for women, 1.31 for men).
Conclusions: Psychologic distress has an independent effect on medically certified sickness absence. The identification of employees with high job strain and the improvement of their working conditions should be considered as an important target in the prevention of adverse consequences of psychologic distress.