Incidence and factors associated with hepatitis B surface antigen seroclearance in patients co-infected with HBV/HIV during antiretroviral therapy in Guangdong, China

Background: Hepatitis B surface antigen (HBsAg) clearance is vital for a functional cure of hepatitis B virus (HBV) infection. However, the incidence and predictors of HBsAg seroclearance in patients co-infected with HBV and human immunodeficiency virus (HIV) remain largely unknown in Guangdong, China. Methods: Between 2009 and 2019, patients co-infected with HBV/HIV undergoing antiretroviral therapy (ART) in Guangzhou Eighth People's Hospital affiliated to Guangzhou Medical University were retrospectively reviewed with the endpoint on December 31, 2020. The incidence and risk factors for HBsAg seroclearance were evaluated using Kaplan-Meier and multivariate Cox regression analyses. Results: A total of 1550 HBV/HIV co-infected patients were included in the study, with the median age of 42 years and 86.0% (1333/1550) males. Further, 98.3% (1524/1550) received ART containing tenofovir disoproxil fumarate (TDF) plus lamivudine (3TC). HBV DNA was examined in 1283 cases at the last follow-up. Over the median 4.7 years of follow-up, 8.1% (126/1550) patients achieved HBsAg seroclearance, among whom 50.8% (64/126) obtained hepatitis B surface antibody, 28.1% (137/488) acquired hepatitis B e antigen seroconversion, and 95.9% (1231/1283) undetectable HBV DNA. Compared with patients who maintained HBsAg positive, cases achieving HBsAg seroclearance showed no differences in age, gender, CD4+ T cell count, alanine aminotransferase (ALT) level, or fibrosis status; however, they presented lower HBV DNA levels, lower HBsAg levels, and higher rates of HBV genotype B at the baseline. Multivariate analysis showed that baseline HBsAg <1500 cutoff index (COI) (adjusted hazard ratio [aHR], 2.74, 95% confidence interval [95% CI]: 1.48-5.09), ALT elevation >2 x upper limit of normal during the first six months after receiving ART (aHR, 2.96, 95% CI: 1.53-5.77), and HBV genotype B (aHR, 3.73, 95% CI: 1.46-9.59) were independent predictors for HBsAg seroclearance (all P <0.01). Conclusions: Long-term TDF-containing ART has high anti-HBV efficacy including relatively high overall HBsAg seroclearance in HBV/HIV co-infected patients. Lower baseline HBsAg levels, HBV genotype B, and elevated ALT levels during the first six months of ART are potential predictors of HBsAg seroclearance.