AbstractThe morbidity and mortality rates of human immunodeficiency virus (HIV)-hepatitis B virus (HBV) coinfection are higher than that of either infection alone. Outcomes and the virological response to antiretrovirals (combination antiretroviral therapy, cART) were explored in HIV/HBV subjects in a cohort of Italian patients treated with cART. A single-center retrospective analysis of patients enrolled from January 2007 to June 2018 was conducted by grouping patients by HBV status and recording baseline viro-immunological features, the history of virological failure, the efficacy of cART in achieving HIV viral undetectability, viral blip detection and viral rebound on follow up. Among 231 enrolled patients, 10 (4.3%) were HBV surface (s) antigen (HBsAg)-positive, 85 (36.8%) were positive for antibodies to HBV c antigen (HBcAb) and with or without antibodies to HBV s antigen (HBsAb), and 136 were (58.9%) HBV-negative. At baseline, HBcAb/HBsAb^+/−-positive patients had lower CD4+ cell counts and CD4+ nadirs (188 cell/mmc, IQR 78–334, p = 0.02 and 176 cell/mmc, IQR 52–284, p = 0,001, respectively). There were significantly higher numbers of AIDS and non-AIDS events in the HBcAb⁺/HBsAb^+/−-positive subjects than in the HBV-negative patients (41.1% vs 19.1%, p = 0.002 and 56.5% vs 28.7%, respectively, p ≤ 0.0001); additionally, HIV viremia undetectability was achieved a significantly longer time after cART was begun in the former than in the latter population (6 vs 4 months, p = 0.0001). Cox multivariable analysis confirmed that after starting cART, an HBcAb⁺/HBsAb^+/−-positive status is a risk factor for a lower odds of achieving virological success and a higher risk of experiencing virological rebound (AHR 0.63, CI 95% 0.46–0.87, p = 0.004 and AHR 2.52, CI 95% 1.09–5.80, p = 0.030). HBcAb-positive status resulted in a delay in achieving HIV < 50 copies/mL and the appearance of viral rebound in course of cART, hence it is related to a poor control of HIV infection in a population of coinfected patients.