How does lowering psychosocial risks influence sickness absence? A prospective cohort study analyzed as a quasi-experiment

Background We examined how reducing work-related psychosocial stressors affected long-term sickness absence of younger and older employees.Methods We used data from 43 843 public sector employees in Finland who participated in surveys in 2018 and 2020. We assessed psychosocial factors, such as job demands, job control, work effort, job rewards and worktime control. We obtained sickness absence data from registers for spells longer than 10 consecutive working days. We applied age-specific propensity score weighting and generalized linear models to estimate the effects of changes in psychosocial factors between 2018 and 2020 on sickness absence in 2020.Results Among employees under 50 years, increasing job rewards by 1 SD reduced the risk of sickness absence by 17% [risk ratio (RR) 0.83, 95% CI 0.72-0.96]. Among employees aged 50 years or older, decreasing job demands by 1 SD reduced the risk of sickness absence by 13% (RR 0.87, 95% CI 0.78-0.98), and increasing job control by 1 SD reduced the risk by 12% (RR 0.88, 95% CI 0.76-1.01). Changes in efforts and worktime control had no significant associations with sickness absence.Conclusions Reducing psychosocial stressors can lower the occurrence of long-term sickness absence, but the associations differ by age group. Younger workers benefit more from enhancing job rewards, while older workers benefit more from lowering job demands and increasing job control. To establish the causal impact of psychosocial risk reduction on sickness absence across age groups, future research should employ randomized controlled trials as the methodological approach.