Physical and mental health functioning after all-cause and diagnosis-specific sickness absence: a register-linkage follow-up study among ageing employees

BACKGROUND Sickness absence has been shown to be a risk marker for severe future health outcomes, such as disability retirement and premature death. However, it is poorly understood how all-cause and diagnosis-specific sickness absence is reflected in subsequent physical and mental health functioning over time. The aim of this study was to examine the association of all-cause and diagnosis-specific sickness absence with subsequent changes in physical and mental health functioning among ageing municipal employees. METHODS Prospective survey and register data from the Finnish Helsinki Health Study and the Social Insurance Institution of Finland were used. Register based records for medically certified all-cause and diagnostic-specific sickness absence spells (>14 consecutive calendar days) in 2004-2007 were examined in relation to subsequent physical and mental health functioning measured by Short-Form 36 questionnaire in 2007 and 2012. In total, 3079 respondents who were continuously employed over the sickness absence follow-up were included in the analyses. Repeated-measures analysis was used to examine the associations. RESULTS During the 3-year follow-up, 30% of the participants had at least one spell of medically certified sickness absence. All-cause sickness absence was associated with lower subsequent physical and mental health functioning in a stepwise manner: the more absence days, the poorer the subsequent physical and mental health functioning. These differences remained but narrowed slightly during the follow-up. Furthermore, the adverse association for physical health functioning was strongest among those with sickness absence due to diseases of musculoskeletal or respiratory systems, and on mental functioning among those with sickness absence due to mental disorders. CONCLUSIONS Sickness absence showed a persistent adverse stepwise association with subsequent physical and mental health functioning. Evidence on health-related outcomes after long-term sickness absence may provide useful information for targeted interventions to promote health and workability.