Hepatitis B virus reactivation in patients with rheumatoid arthritis: Analysis of the National Database of Japan

Summary This study aimed to determine the incidence and risk factors for hepatitis B virus (HBV) reactivation in patients with rheumatoid arthritis (RA) undergoing immunosuppressive therapy. The National Database of Japan, in which insurance claim data have been comprehensively accumulated, was utilized. The subjects were 76 641 RA patients who were plausibly initiated on immunosuppressive therapy from April 2013 to March 2014. Laboratory tests of the hepatitis B surface antigen, anti‐hepatitis B virus surface antibody, and anti‐hepatitis B virus core antibody were performed in 28.23%, 12.52% and 14.63% of patients, respectively, when the therapy was initiated. We found that HBV reactivation and fulminant hepatitis occurred in both the patients with and without HBV DNA monitoring, indicating insufficient monitoring in Japan during the study. The cumulative incidence of HBV reactivation over 24 months was 1.57% (95% confidence interval [CI] = 1.28%‐1.92%) in the monitoring group, which consisted of those with resolved HBV infection. Glucocorticoid administration was a potent risk factor for HBV reactivation (hazard ratio [HR] = 1.70, 95% CI = 1.26‐2.29, P = .001 in all subjects, and HR = 1.82, 95% CI = 1.18‐2.81, P = .007 in the nonmonitoring group), although it was not statistically significant in the monitoring group (HR = 1.49, 95% CI = 0.99‐2.26 and P = .057). No significant risk difference was observed between single administration of methotrexate and biological drugs.