Combined exposure to heavy physical workload and low job control and the risk of disability pension: A cohort study of employed men and women in Sweden

Objective To investigate the separate and combined effects of overall heavy physical workload (PWL) and low decision authority on all-cause disability pension (DP) or musculoskeletal DP. Methods This study uses a sample of 1,804,242 Swedish workers aged 44–63 at the 2009 baseline. Job Exposure Matrices (JEMs) estimated exposure to PWL and decision authority. Mean JEM values were linked to occupational codes, then split into tertiles and combined. DP cases were taken from register data from 2010 to 2019. Cox regression models estimated sex-specific Hazard Ratios (HR) with 95% confidence intervals (95% CI). The Synergy Index (SI) estimated interaction effects. Results Heavy physical workload and low decision authority were associated with an increased risk of DP. Workers with combined exposure to heavy PWL and low decision authority often had greater risks of all-cause DP or musculoskeletal DP than when adding the effects of the single exposures. The results for the SI were above 1 for all-cause DP (men: SI 1.35 95%CI 1.18–1.55, women: SI 1.19 95%CI 1.05–1.35) and musculoskeletal disorder DP (men: SI 1.35 95%CI 1.08–1.69, women: 1.13 95%CI 0.85–1.49). After adjustment, the estimates for SI remained above 1 but were not statistically significant. Conclusion Heavy physical workload and low decision authority were separately associated with DP. The combination of heavy PWL and low decision authority was often associated with higher risks of DP than would be expected from adding the effects of the single exposures. Increasing decision authority among workers with heavy PWL could help reduce the risk of DP.