Fujita M, et al. - Using National Database of Japan, researchers determined the incidence and risk factors for hepatitis B virus (HBV) reactivation in patients with rheumatoid arthritis (RA) undergoing immunosuppressive therapy. A total of 76,641 RA patients who were plausibly initiated on immunosuppressive therapy from April 2013 to March 2014 were analyzed suggesting occurrence of HBV reactivation and fulminant hepatitis in both the patients with and without HBV DNA monitoring, indicating insufficient monitoring in Japan during the study. Glucocorticoid administration was noted to be a potent risk factor for HBV reactivation, although it was not statistically significant in patients with monitoring. Single administration of methotrexate and biological drugs showed no significant risk difference.