Prophylactic Effect of Lamivudine-Based Antiretroviral Therapy on Incident Hepatitis B Virus Infection Among HIV-Infected Patients

TO THE EDITOR—Patients with human immunodeficiency virus (HIV) infection are at high risk for hepatitis B virus (HBV) infection because of shared modes of transmission [1]. The presence of HBV coinfection complicates the management of HIV and increases the morbidity and mortality of HIV-infected patients [2]. A recent serological follow-up study conducted by Gatanaga and colleagues concluded that lamivudineor tenofovir disoproxil fumarate (tenofovir)–containing antiretroviral therapy (ART) conferred protection against incident HBV infections among HIV-infected individuals in Japan [3], where the prevalence of chronic HBV infection in the general population and HIV-infected patients is 2%–7% and 6.4%, respectively [4, 5]. Although the finding that the risk of incident HBV infection could be reduced by nearly 90% for those who received lamivudineor tenofovir-containing ART is encouraging, we are concerned about the complacency with the prophylactic effect of lamivudine or tenofovir among the HIV-treating physicians and the generalizability of the findings to areas of higher endemicity for chronic HBV infection. We believe that the risk of incident HBV infection will vary with the prevalence of HBV infection and the rate of vaccination against HBV among the HIV-infected patients and the general population. In Taiwan, the prevalence of chronic HBV infection in the general population and HIV-infected patients is 15%–20% and 18%–20%, respectively [4, 6–8]. In our previous longitudinal follow-up study that was published in Clinical Infectious Diseases [7], we have identified 65 HIV-infected individuals who tested negative for any HBV serological markers (HBV surface antigen [HBsAg], anti-HBV core antibody [anti-HBc], and anti-HBsAg antibody [anti-HBs]) at baseline. Of the 65 patients, 61 eventually received lamivudinecontaining ART for HIV. None of the patients received anti-HBV agents other than lamivudine (interferon, tenofovir, entecavir, adefovir, or telbivudine). During the follow-up, changes of HBV serological markers were detected in the sequentially stocked blood samples from 30 patients, including 4 patients with HBs antigenemia, 8 with positivity for antiHBc and anti-HBs, 13 with isolated antiHBc, and 5 with positivity for anti-HBs only (Table 1). Using the same definitions to estimate the incidence rate of HBV infections as those by Gatanaga and colleagues [3], 4 incident HBV infections occurred in the patients without lamivudine-containing ART and 21 in those with lamivudine-containing ART