LAUSR

Reactivation of hepatitis B virus (HBV) has been reported in hepatitis C virus–infected individuals receiving direct‐acting antiviral (DAA) therapy. The overall risk among patients with current or prior HBV infection in the context of DAA treatment is unknown. The aim of this evaluation was to identify and characterize HBV reactivation among veterans treated with oral DAA therapy. This retrospective evaluation included 62,290 hepatitis C virus–infected veterans completing oral DAA treatment. Baseline HBV infection status for each veteran was identified from HBV laboratory data performed prior to DAA initiation. To assess for HBV reactivation and hepatitis we identified all hepatitis B surface antigen (HBsAg), HBV DNA, and alanine aminotransferase results obtained while on DAA treatment or 7 days after. HBV reactivation was defined as a >1000 IU/mL increase in HBV DNA or HBsAg detection in a person who was previously negative. Prior to DAA treatment 85.5% (53,784/62,920) had HBsAg testing and 0.70% (377/53,784) were positive; 84.6% (53,237/62,920) had a hepatitis B surface antibody test, of which 42.2% (22,479/53,237) were positive. In all, 9 of 62,290 patients treated with DAAs had evidence of HBV reactivation occurring while on DAA treatment. Eight occurred in patients known to be HBsAg‐positive, and 1 occurred in a patient known to be isolated hepatitis B core antibody–positive. Seventeen other patients had small increases in HBV DNA levels that did not qualify as HBV reactivation. Only 3 of the 9 patients identified with HBV reactivation in this cohort exhibited peak alanine aminotransferase elevations >2 times the upper limit of normal. Conclusion: HBV reactivation of varying severity, even in the setting of isolated hepatitis B core antibody, with or without accompanying hepatitis can occur—though the occurrence of accompanying severe hepatitis was rare. (Hepatology 2017;66:27–36).