Predictors of work disability during the first 3 years after diagnosis in a national rheumatoid arthritis inception cohort

Objective: To identify predictors of sick leave and disability pension in patients with early rheumatoid arthritis (RA). Methods: Individuals aged 19-59 years diagnosed with early RA (=12 months symptom duration) were identified in the Swedish Rheumatology Quality Register (1999-2007; n=3029). We retrieved days of sick leave and disability pension from the Swedish Social Insurance Agency and baseline predictors of total work days lost during 3 years after RA diagnosis were investigated using linear regression. Due to effect modification by baseline work ability (defined as work days lost the month before diagnosis), analyses were stratified into three categories: full=0 work days lost the month before diagnosis; partial=1-29 work days lost; and none=30 work days lost. Results: 71% of patients with full baseline work ability still had full work ability after 3 years compared with 36% (p<0.001) and 18% (p<0.001) of those with partial and no work ability at baseline, respectively. Elevated baseline levels of HAQ and DAS28, higher age, lower education level and unemployment were associated with more work days lost during 3 years in all strata of baseline work ability (all p<0.05). In a separate analysis, more objective variables (ESR, CRP and swollen joints) were not. Generally, the largest regression coefficients were seen for patients with partial baseline work ability. Conclusions: Work ability at RA diagnosis was the most important predictor of 3-year sick leave and disability pension. Taking this into account, HAQ, DAS28, age and education level were also significant predictors, whereas ESR and CRP were not.