Joint contributions of psychological distress and demanding working conditions to short and long sickness absence among young and early midlife municipal employees

This register-linked follow-up study examined whether psychological distress and demanding working conditions are jointly associated with short and long sickness absence (SA) periods among young and midlife Finnish public sector employees. We linked the Helsinki Health Study survey (response rate 51.5%, 80% women, ages 19-39 years in 2017) on psychological distress, physically and mentally strenuous work, and hours per day spent in physical work with the employer's SA register (n = 3609, mean follow-up of 2.1 years). We calculated rate ratios (RRs) and their 95% confidence intervals (CIs) for short (1-7 days) and long (8+ days) SA periods using negative binomial regression models. Additionally, we calculated the synergistic interaction between psychological distress and working conditions. Most (88%) participants had at least one short and 31% at least one long SA period. Participants with psychological distress and exposure to demanding working conditions had the highest RRs for long SA periods (physically strenuous work: RR: 2.27, CI: 1.87-2.77; mentally strenuous work: RR: 2.02, CI: 1.66-2.46; ≥3 h per day spent in physical work: RR: 2.41, CI: 1.94-2.99). The interactions for long SA were negative for physically demanding working conditions, but additive for mentally strenuous work. The associations were weaker for short SA periods. Adjusting for other covariates only slightly attenuated these associations. Psychological distress and demanding working conditions were jointly associated with short and long SA periods. Both individual- and workplace-related risk factors for SA need to be considered when planning preventive actions.