Long-term work disability in patients with psoriatic arthritis treated with anti-tumour necrosis factor: a population-based regional Swedish cohort study

Objective To study long-term work disability before and after tumour necrosis factor (TNF)-antagonist therapy in patients with psoriatic arthritis (PsA). Methods Using the population-based South Swedish Arthritis Treatment Group Register, we identified 191 patients with PsA (median age 43years, range 18-58years, 54% men), who between January 2003 and December 2007 started treatment with adalimumab, etanercept or infliximab. We linked data to the Swedish Social Insurance Agency and calculated the proportion of work disability in 30-day intervals from 12months before the start of treatment until 3years after. For each patient with PsA we randomly selected four matched reference subjects from the general population. Results At treatment initiation 67% of the patients with PsA were work disabledthat is, either on sick leave (41.5%) or receiving a disability pension (25.3%). Patients sustaining treatment were, on average, work disabled 12.5days a month at treatment initiation declining to 10.6days a month after 3years of treatment. Patients for whom the first treatment course failed were work disabled 16.5days at treatment start decreasing to 15.6days after 3years. The background population were 2.5days and 3.0days off work each month, respectively. Regression modelling identified prior work disability status, anti-TNF treatment failure, higher age, female gender and longer disease duration as significant predictors of working disability. Conclusions There was a decline in net work disability after initiation of anti-TNF treatment in patients with PsA. Patients withdrawing from treatment had a 50% increased risk of being work disabled. Prior work disability, higher age, female gender and longer disease duration were also associated with long-term work disability.