Interaction effects of physical and psychosocial working conditions on the risk of disability pension among nursing professionals and care assistants in Sweden: A prospective study.

Background: Nursing professionals and care assistants are often subject to a combination of negative physical and psychosocial work environment factors, but most disability pension studies on such occupations have focused on one or the other of these factors. As they often coexist, there are reasons to assume that simultaneously being exposed to both types of exposures will increase the risk of disability more than being exposed to either.

Objectives: The study examined combinations of physical and psychosocial work conditions as predictors of future disability pension among nursing professionals and care assistants in Sweden.

Participants: The study was based on a random and representative sample of 79,004 participants in any of the Swedish Work Environment Surveys from 1993 to 2013. A total of 2576 nursing professionals, 10,175 care assistants, and 66,253 workers in other occupations were included.

Methods: Information on background factors and disability pension was obtained from population registers. Cox proportional hazard regressions with 95% confidence intervals (CI) were performed to study if pairs of combinations of physical and psychosocial factors were related to an increased risk of disability pension. Additionally, measures of synergistic effects were estimated. The analyses were stratified on occupation group, with adjustment for selected confounders.

Results: The results indicated increased hazard ratios (HR) for disability pension for most combinations of physical and psychosocial working conditions. The hazard ratios for joint exposure to high demands and heavy physical work were high among both nursing professionals (HR 1.91; CI 1.06-3.44) and care assistants (HR 2.09; CI 1.63-2.69). Also, the combination of high demands and strenuous postures resulted in significantly elevated risks of disability pension among nursing professionals (HR 1.95; CI 1.20-3.16) and care assistants (HR 2.18; CI 1.71-2.77). The HRs for joint exposure to low control and both heavy physical work and strenuous postures were significant among all other occupations (HR 2.30; CI 2.05-2.58 and HR 2.24; CI 2.01-2.51), and among care assistants (HR 1.52; CI 1.26-1.85 and HR 1.61; CI 1.34-1.93), but not significant among nursing professionals. The synergistic effects on disability pension from combined exposures were generally positive among all three occupational groups.

Conclusion: Nursing professionals and care assistants exposed to both negative physical and psychosocial conditions had an increased risk of disability pension. A synergistic effect with respect to disability pension was found among care assistants who reported low control and strenuous postures at work.