Background Employees’ health is dependent on individual and social factors operating from across the life course. Studies have shown that negative life events during childhood or low socioeconomic status (SES) in adulthood may predict decreased labour market participation. However, the combined effects of childhood adversities and low SES in adulthood on work disability are not known.

Methods We included 34 384 employed Finnish Public Sector study participants who responded to questions about childhood adversities (none versus any adversity, e.g., parental divorce or financial difficulties) in 2008, and whose adult SES (based on occupational status) in 2008 was available. We categorised exposure into four groups: neither (reference), childhood adversity only, low SES only, or both. Participants were followed from 2009 until the first period of register-based work disability (sickness absence >9 days or disability pension) due to any cause, musculoskeletal or mental disorders; retirement; death; or end of follow-up (December 2011). We ran cox proportional hazard models adjusted for behavioural, health- and work-related covariates.

Results When compared to those with neither exposure, hazard ratio (HR) for work disability from any cause was increased among participants with childhood adversity, with low SES, and those with both exposures. Low adult SES was a stronger predictor (HR 2.38, 95% CI=2.14 to 2.64) of disability due to musculoskeletal disorders than childhood adversity (1.11, 95% CI=1.00 to 1.23). The difference between the exposures as predictors of disability due to mental disorders was smaller (adversity: 1.40, 95% CI=1.23 to 1.59; low SES: 1.21, 95% CI=1.03 to 1.42). The highest risk was observed in those with both exposures (2.53, 95% CI=2.29 to 2.79 for musculoskeletal disability).

Discussion Exposure to adversities in childhood and low SES in adulthood were associated with work disability. Exposure to both these risk factors was associated with the highest work disability risk, although this was additive rather than synergistic effect. Childhood adversity was associated with disability due to mental disorders in particular, whereas low adult SES was more strongly associated with disability due to musculoskeletal disorders.