Introduction: Hepatitis B surface antigen (HBsAg) loss is a rare event among persons with hepatitis B virus (HBV) monoinfection but seems to happen more frequently in people with HIV (PWH). We assessed the proportion of PWH/HBV coinfection who experienced HBsAg loss during long-term tenofovir-therapy and evaluated its association with quantitative HBsAg (qHBsAg) levels at tenofovir start.

Methods: All Swiss HIV Cohort Study participants with two or more positive HBsAg measurements more than 6 months apart, and at least 4 years of tenofovir-containing antiretroviral therapy (ART), were considered. Our main outcomes were the loss of HBsAg during the first 2 years of tenofovir therapy and until the last available follow-up. We explored the association between qHBsAg levels at tenofovir start and HBsAg loss using multivariable logistic regression adjusted for potential confounders.

Results: A total of 272 PWH and HBV coinfection were included. Median age was 41 years (IQR 36-46) and 81% (221) were men. At tenofovir start, 62% (169/272) received prior HBV active therapy, 49% (110/224) were hepatitis B e antigen (HBeAg)-positive, 82% (222/272) had detectable HBV DNA (median 4.0 log10 IU/mL, IQR 2.1-7.5) and 19% (46/242) had low qHBsAg, defined as <1000 IU/mL. HBsAg loss was observed in 7% (19/272) of participants during the first 2 years of tenofovir-containing ART and in 16% (43/272) after a median follow-up time of 8.4 years (IQR 2.6-15.8). At the last follow-up, 59% (16/27) of those with HBsAg loss had seroconverted for detectable anti-HBs antibodies. In multivariable analyses, low qHBsAg at tenofovir start (OR 5.3, 95% CI 1.6-17.8) was a significant predictor of HBsAg loss.

Conclusion: We found high rates of HBsAg loss in PWH and HBV coinfection on long-term tenofovir-containing ART, most of whom had low qHBsAg at tenofovir start.