Introduction: Osteoarthritis is one of the most common types of musculoskeletal diagnoses also among working-age populations, and often leads to long-term sickness absence (SA) spells or even disability pension (DP).
The aim: was to identify future trajectories of days of SA and/or DP among people with a new SA spell due to osteoarthritis that became ≥21 long, and to investigate sociodemographic and morbidity characteristics of individuals in identified trajectories.
Methods: This is a prospective population-based cohort study using data from several Swedish registers. We studied future SA/DP among all 4894 individuals aged 16-64 years who, during the first 6 months of 2010, had an incident SA spell due to osteoarthritis (ICD-10 codes M15-19) ≥21 days. Using group-based trajectory modelling, we identified trajectories of mean SA/DP net days/month and 95% CIs for the 13 months from the 21st day of the index SA spell. Sociodemographic and morbidity characteristics were compared by χ2 tests and multinomial logistic regression.
Results: We identified five trajectories of SA/DP days: 'fast decrease' (36% of the cohort), 'medium fast decrease' (29%), 'slow decrease' (15%), 'fluctuating' (12%) and 'late decrease' (8%). Individuals in the two trajectories who still had SA/DP days at end of follow-up (late decrease and fluctuating) were more likely to be older, born outside the EU and have indicators of more severe morbidity than those in the other trajectories.
Conclusion: Five trajectories of future SA/DP days were identified; 80% of the cohort belonged to trajectories with no SA/DP by the end of follow-up. Identifying trajectories of future SA/DP provides new insights regarding the developments of SA/DP over time among people on SA due to osteoarthritis; not only days in the initial SA spell but also in new spells during follow-up need to be included for a better understanding.
Keywords: disability pension; osteoarthritis; return to work; sick leave.
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