Sickness absence due to back pain or depressive episode and the risk of all-cause and diagnosis-specific disability pension: A Swedish cohort study of 4,823,069 individuals

Background: The aim of this study was to investigate the associations between sickness absence due to back pain or depressive episode with future all-cause and diagnosis-specific disability pension, while adjusting for comorbidity and socio-demographics, for all and stratifying for sex. Method: In total, 4,823,069 individuals aged 16-64 years, living in Sweden at the end of 2004, not on old-age or disability pension in 2005 and without ongoing sickness absence at the turn of 2004/2005 formed the study population. Crude and adjusted hazard ratios (HRs) for all-cause and diagnosis-specific disability pension (2006-2010) in relation to diagnosis-specific sickness absence with sickness benefits paid by the Social Insurance Agency were estimated using Cox regression. Results: The HR for all-cause disability pension was 7.52 (7.25-7.52) in individuals with an incident sick-leave spell due to back pain, compared to individuals without sickness absence in 2005 in the fully adjusted (socio-demographics and comorbidity) model. The fully adjusted (multivariate) HRs for diagnosis-specific disability pension were musculoskeletal diagnoses 23.87 (22.75-25.04), mental 2.49 (2.27-2.73) or all other diagnoses, 3.44 (3.17-3.75). In individuals with an incident sick-leave spell due to a depressive episode in 2005, the multivariate adjusted HR for all-cause disability pension was 12.87 (12.42-13.35), while the multivariate HRs for disability pension due to musculoskeletal diagnoses were 4.39 (3.89-4.96), for mental diagnoses 25.32 (24.29-26.38) and for all other somatic diagnoses 3.44 (3.09-3.82). Men who were sickness absent due to a depressive episode had a higher HR for disability pension compared to women. Conclusion: Results indicate that sickness absence due to a depressive episode or back pain is a strong risk factor for a future disability pension due to mental, musculoskeletal or other somatic diagnoses.