Background Although there is some literature on the impact of Ankylosing Spondylitis (AS) on the employment status or work disability (WD), the far majority of these studies are cross-sectional analyses and few compared work outcome with the general population.
Objectives To understand the long-term impact of AS on participation in labour force over 12 years in a prospective cohort study, to identify predictors of an adverse work outcome (AWO) and to compare the incidence of WD over time with the general population.
Methods Work related information and clinical characteristics were obtained from patients followed in the Outcome in AS International Study (OASIS). Patients who were at risk of having an AWO were included in the analysis, i.e. workers (either at baseline or resuming work later). AWO was defined as WD or a reduction in the number of working hours. Survival analysis was used to investigate AWO. With Cox regression, first baseline and secondly time-varying predictors were identified; the latter adjusted for 2 time dependent variables (change in social security system and market availability of anti-TNF). Incidence rate for WD among Dutch patients was compared with the general population using indirect standardization.
Results Of 215 patients in the OASIS cohort, 139 (65%) were at risk for AWO (mean age 38.3 (SD 9.9) years, 75 % male, 81% HLA-B27, mean disease duration 9 (SD 6.8) years), of whom 11% (n=15) were not working at baseline but resumed work over time. A stepwise multivariable Cox analysis showed that higher baseline BASFI (HR 1.19; 95% CI 1.01-1.41) and Dutch origin (HR 3.85; 95% CI 1.37-10.84) predicted long-term AOW. In the time-lagged prediction analysis, only a higher BASFI (HR 1.27; 95%CI 1.08-1.50) significantly predicted AWO over time. Of 130 Dutch patients in working age, 9% (n=12) became WD over 12 years. The incidence of WD over 12 years was 2.9 (95% CI 1.2-4.6) and 1.22 (-0.42 - 2.87) times higher compared with the general population, for males and females, respectively.
Conclusions Even in AS patients with already long disease duration, a substantial proportion remains at risk for an AWO. Self-reported physical function (BASFI) and system characteristics consistently influence AWO.
Disclosure of Interest None Declared
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