OBJECTIVES: Risk of hepatitis B virus (HBV) reactivation has increased because of advances in immunosuppressive therapies. People having a previously-resolved HBV infection and those with serum HBs-antigen positivity are likely to develop liver injuries after the therapies. However, the risk of HBV reactivation for rheumatoid arthritis (RA) patients is still unclear. The aim of this study was to clarify the significance of HBV reactivation in RA patients undergoing immunosuppressive treatments.

METHODS: Adult patients who had been diagnosed with RA between 1 April 2011 and 31 March 2015 were extracted from the Medical Information Analysis (MIA) databank managed by the Clinical Research Center at the National Hospital Organization (NHO) Headquarters. Medical centers N and B are NHO hospitals located south in Japan. We conducted chart reviews in these hospitals to identify the cases with reactivation of HBV and to investigate the incidence of it.

RESULTS: For verifying the HBV reactivation, 103 and 89 candidates were abstracted and chart reviews were conducted in the two hospitals. Among them, 47 and 71 patients underwent periodic HBV-DNA testing while receiving immunosuppressive therapies, and 35 and 64 of patients had previously-resolved HBV infections (74.5% with 95%CL: 59.7-86.1%, and 90.1% with 95%CL: 80.7%-95.9%, respectively). Incidence rates of HBV reactivation were 3.26 and 0.56 / 100 person-years in the two medical centers.

CONCLUSIONS: Two medical centers had different rates of HBV reactivation. This difference is likely a result of the differences in characteristic and comorbidities of patients who used these medical centers. We plan to evaluate the incidence of HBV reactivation after an immunosuppressive therapy using an administrative database. Because information of changes in serum HBV-DNA levels after immunosuppressive therapies was unavailable in the database, we conducted a chart review. This chart review will be a good sample for our future project.