Objective. To understand the impact of ankylosing spondylitis (AS) on work disability (WD) over 12 years compared with the general population, and explore factors predicting adverse work outcome, defined as new partial WD or reduction in working hours.
Methods. Source of data was the Outcome Assessments in Ankylosing Spondylitis International Study, which includes patients from The Netherlands, France, and Belgium. Standardized WD rates over time compared to the general population were calculated using indirect standardization (Dutch patients only). Cox survival analyses identified baseline predictors as well as time-varying factors influencing adverse work outcome over 12 years.
Results. Of 215 patients, 55 (26%) were full WD at baseline and 139 (65%) were at risk for adverse work outcome during followup. When compared to the general population, WD over 12 years continued to be increased in Dutch men (incidence rate [IR] 2.9 [95% confidence interval (95% CI) 1.2, 4.6]), but less clearly for women (IR 1.2 [95% CI -0.4, 2.9]). Within the entire sample, baseline predictors of adverse work outcome over 12 years were residence in The Netherlands (versus France or Belgium) (hazard ratio [HR] 3.4 [95% CI 1.4, 8.4]) and worse Bath Ankylosing Spondylitis Functional Index (BASFI) (HR 1.2 [95% CI 1.0, 1.4]). Time-varying predictors over 12 years were residence in The Netherlands, uveitis, and either BASFI or Bath Ankylosing Spondylitis Disease Activity Index with age and inflammatory bowel disease.
Conclusion. Although WD was already prevalent at inclusion in the cohort, a substantial proportion of patients incurred further adverse work outcome over 12 years. In addition to country of residence, uveitis, age, and self-reported physical function or disease activity predicted long-term adverse work outcome.