BackgroundWhether hepatitis C virus (HCV) infection increases the risk of rheumatic disorders and whether the associated risk is reversed by anti-HCV therapy remain elusive. We aimed to investigate these topics. MethodsA nationwide population-based cohort study of Taiwan National Health Insurance Research Database (TNHIRD) was conducted. ResultsOf 19,298,735 subjects, 3 TNHIRD cohorts (1:4:4, propensity score-matched), including HCV-treated (6,919 HCV-infected subjects with interferon and ribavirin therapy > 6 months), HCV-untreated (n=27,676) and HCV-uninfected (n=27,676) cohorts, were enrolled and had been followed since 2003 to 2015. HCV-uninfected cohort had the lowest 11-year cumulative incidence of rheumatic disorders [9.535%; 95% confidence interval (CI): 8.416~10.734%] (p<0.0001), while HCV-treated (14.95%; 12.417~17.704%) and HCV-untreated (14.999%; 13.585~16.479%) cohorts showed no difference in the cumulative incidences of rheumatic disorders (p=0.8316). Multivariate analyses showed, HCV infection [hazard ratio (HR):1.671; 95% CI HR: 1.562-1.788, p<0.0001], female sex (1.67; 1.565-1.782, p<0.0001), age> 49 years (1.168; 1.088-1.253, p<0.0001), Charlson comorbidity index > 1 (1.156; 1.074-1.245, p=0.0001), liver cirrhosis (0.795; 0.674-0.937, p=0.0062), chronic obstruction pulmonary disease (1.244; 1.134-1.364, p<0.0001), end stage renal disease (0.732; 0.549-0.974, p=0.0326), diabetes mellitus (0.91; 0.835-0.993, p=0.0333) and dyslipidemia (1.205; 1.108-1.31, p<0.0001) were associated with incident rheumatic disorders. Among the 3 cohorts, the untreated cohort had the highest cumulative incidence of overall mortality (29.163%; 27.218-31.133%, p<0.0001), while the treated (13.662%; 11.389-16.140%) and un-infected (9.99%; 8.548-11.559%) cohorts had indifferent mortalities (p=0.1796). ConclusionsHCV infection, baseline demographics and comorbidities were associated with the risks of rheumatic disorders. Although HCV-associated risk of rheumatic disorders might not be reversed by interferon-based anti-HCV therapy, which reduced the overall mortality in HCV-infected patients.