1 Division of Clinical Care and Research, Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, United States.
Hepatitis B surface antigen (HBsAg) level plays an important role in conjunction with other markers such as hepatitis B envelope antigen (HBeAg) and hepatitis B virus (HBV) deoxyribonucleic acid levels to predict disease activity in chronic Hepatitis B (CHB). Quantification of HBsAg is useful in differentiating carriers from active hepatitis in HBeAg negative patients, and current guidelines recommend monitoring of pegylated interferon alpha treatment in CHB infection. However, there are only few studies about the role of quantitative HBsAg (qHBsAg) monitoring in HIV-HBV coinfected patients. Studies have shown that tenofovir based antiretroviral therapy regimen leads to a very slow decline in HBsAg levels and a predicted time of 10-42 years to lose the HBsAg, in majority of patients. Rapid drop in HBsAg levels and gain in CD4 within the 1st year of treatment and low baseline HBsAg level are associated with faster seroconversion. The reported rate of HBsAg loss in this population is < 15%. In this review, we discuss utility of qHBsAg in monitoring disease activity and treatment in HIV-HBV coinfected population.