Long-term physical workload in middle age and disability pension in men and women: a follow-up study of Swedish cohorts

PURPOSE The study investigates the association between level of long-term physical workload in middle age and disability pension (DP) before 61 years of age with adjustments made for early life factors, level of education, and psychosocial working conditions. Associations with DP overall, DP due to musculoskeletal disorders and DP due to psychiatric disorders were examined. METHODS The study is based on cohorts of 21,809 Swedish men and women born in 1948 and 1953, with data on physical workload estimated with a job exposure matrix based on occupational titles in 1985 and 1990 and follow-up data on diagnosis-specific DP in the years 1991-2009. Data on paternal education and intelligence were collected in primary school. Data on level of education were taken from administrative records. Data on psychosocial working conditions were estimated with a job exposure matrix based on occupational titles in 1990. RESULTS Long-term exposure to high physical workload measured 5 years apart at around age 40 was strongly associated with DP due to musculoskeletal disorders up to the age of 61 among both men (HR 5.44, 95 % CI 3.35-8.84) and women (HR 3.82, CI 95 % 2.88-5.08). For women, the association between high physical load and overall DP was also significantly increased (HR 2.33, CI 95 % 1.92-2.82). The increased risks remained but were clearly attenuated after adjustments for fathers' education, IQ in childhood, achieved education and level of control at work. CONCLUSIONS Exposure to high physical workload is associated with long-term risk of DP due to musculoskeletal disorders, even though adjustments for early life factors, level of education and psychosocial working conditions clearly attenuated the risks.