Real-World Effectiveness of Antiviral Prophylaxis for Preventing Hepatitis B Virus (HBV) Reactivation in Patients Undergoing Immunosuppressive Therapy.

This study evaluated the characteristics of patients receiving prophylactic antiviral therapy against hepatitis B virus (HBV) infection due to immunosuppressive treatment and assessed the occurrence of HBV reactivation. Between January 2015 and January 2025, 199 adult patients followed in the Infectious Diseases and Clinical Microbiology outpatient clinic who had received prophylactic oral antiviral therapy were retrospectively analyzed. Demographic characteristics, underlying diseases, immunosuppressive treatment history, HBV serological results, biochemical and virological findings, and prophylactic antiviral regimens were recorded. Patients were stratified into low-, moderate-, and high-risk groups according to the American Gastroenterological Association (AGA) 2025 classification. The mean age was 60.4 years; 50.3% of patients were male. Serologically, 26.6% were HBsAg- and anti-HBc-positive, 33.2% showed isolated anti-HBc positivity, and 40.2% had dual anti-HBc/anti-HBs positivity. The risk of HBV reactivation was low in 41.2%, moderate in 22.1%, and high in 36.7% of patients. Prophylaxis consisted of entecavir in 76.4%, tenofovir alafenamide in 13.1%, and tenofovir disoproxil fumarate in 10.5%. HBV reactivation occurred in only one patient, who had discontinued treatment. These findings emphasize the importance of HBV screening and timely prophylactic antiviral therapy in patients undergoing immunosuppression to effectively prevent HBV reactivation.