Changes in hepatitis B virus surface antibody titer and risk of hepatitis B reactivation in HBsAg-negative/HBcAb-positive patients undergoing biologic therapy for rheumatic diseases: a prospective cohort study.

Background: Our aim was to investigate dynamic changes in hepatitis B virus (HBV) surface antibody (HBsAb) titer and the associated risk of HBV reactivation and clinical course in patients with HBV surface antigen negative/core antibody positive (HBsAg/HBcAb) serostatus during antirheumatic therapy with biologic agents.

Methods: In a prospective study from January 2013 to June 2017, we monitored the HBV serostatus of HBsAg/HBcAb patients undergoing biologic therapy for rheumatic diseases. From HBsAb titers at baseline and subsequent time points, we calculated the person-years (PY) contributed by patients with different HBsAb levels: < 10 mIU/mL (negative); 10-100 mIU/mL (low); and > 100 mIU/mL (high).