Nationwide trends in physical disability among rheumatoid arthritis patients in Korea (2010–2022): A retrospective cohort study based on national registry data

Background Whether the burden of legally certified disability among patients with rheumatoid arthritis (RA) has decreased in the modern treatment era is uncertain, particularly in Asia. We investigated trends in registered and physical disability among Korean patients with RA. Methods Using National Health Insurance Service data (patient-level 50% random sample), we identified patients aged ≥19 years with seropositive RA registered in the copayment assistance program for rare and intractable diseases in 2010–2022. Disability status, including physical disability (certified musculoskeletal impairment), came from the national disability registry. We estimated annual prevalence and, in newly diagnosed patients, incidence per 1,000 person-years, and compared the results with national disability statistics. Results The number of patients with seropositive RA identified in the database and included in this study was 33,992 in 2010 and 67,844 in 2022. The prevalence of registered disability declined from 20.3% to 14.6% and that of physical disability from 17.4% to 10.9% (both p for trend <0.001) in both sexes. Among 61,086 newly diagnosed patients, the incidence of registered disability did not change (5.08 per 1,000 person-years; annual change −0.9%, p = 0.24), whereas that of physical disability declined by 6.7% per year (p < 0.001). Men had a higher incidence of registered disability than women (6.73 vs. 4.58 per 1,000 person-years), but not of physical disability. Older age (odds ratio [OR] 1.035 per year, 95% CI 1.032–1.039), male sex (OR 1.295, 95% CI 1.174–1.429), and lower income were associated with incident registered disability. In 2022, physical disability remained more prevalent in RA (10.9%) than in the general population (2.3%) and in those aged ≥65 years (7.1%). Conclusions Certified physical disability among Korean patients with RA declined substantially between 2010 and 2022, whereas the incidence of any registered disability remained stable. An excess burden of physical disability compared with the general population persisted.