Higher incidence of rheumatoid arthritis in patients with symptomatic osteoarthritis or osteoarthritis-related surgery: a nationwide, population-based, case–control study in Taiwan

OBJECTIVES To investigate the risk of incident rheumatoid arthritis in patients with symptomatic osteoarthritis or osteoarthritis-related surgery using a nationwide health claims database. DESIGN A nationwide, population-based, case-control study. SETTING Taiwan's National Health Insurance Research Database. PARTICIPANTS A total of 1147 patients (aged 20-100 years) with rheumatoid arthritis and 5735 controls who were frequency-matched for sex, 10-year age interval and year of catastrophic illness certificate application date (index year) were identified. MAIN OUTCOME MEASURE All participants were retrospectively traced, up to 14 years prior to their index year, for diagnosis of osteoarthritis or osteoarthritis-related surgery. Multivariate logistic regression analyses were conducted to quantify the association between rheumatoid arthritis and osteoarthritis. RESULTS The risks of rheumatoid arthritis were significantly higher in patients with symptomatic osteoarthritis (adjusted OR=5.24, p<0.001) and osteoarthritis-related surgery (adjusted OR=2.27, p<0.001). CONCLUSIONS This large nationwide, population-based, case-control study showed a higher risk of rheumatoid arthritis in Taiwanese patients with symptomatic osteoarthritis. Our findings were consistent with the hypothesis that osteoarthritis might be a triggering factor of rheumatoid arthritis in environment-sensitised and genetically susceptible individuals.