[PD Test]Revealed: Hepatitis B viral load critical to infection clearance

Out of about 400 million people with chronic hepatitis B virus (HBV), 75 percent of those infected live in the Asia Pacific region. Since HBV is strongly linked to the development of cirrhosis and liver cancer, the infection rate constitutes a significant public health challenge.

Risk predictors, such as the one detailed in theREVEAL-HBV* study, which trace the natural history of chronic HBV infection, have shown that viral load is a major predictor for clearing viral proteins.

“This risk calculator has very good calculations and [is] also accurate,” said study lead Dr. Chien-Jen Chen, of the Academia Sinica and National Taiwan University in Taipei, Taiwan.

The REVEAL-HBV study was a community-based trial that included 3,087 adults with chronic HBV. Serum samples were collected at baseline between 1991 and 1992, and during follow-up exams. Serum samples were tested for HBV antigens (HBsAg and HBeAg), serum HBV-DNA, and anti-hepatitus C virus serostatus. [Gastroenterology 2010;139:474-482]

Over 24,892 person-years of follow-up, HBsAg seroclearance occurred in 562 participants – a 2.26 percent annual seroclearance rate. The most significant predictor of seroclearance were HBV-DNA levels at baseline, where a higher viral load correlated with lower seroclearance (p<0.001). Conversely, seroclearance was significantly associated with a drop in serum HBV-DNA, with an adjusted odds ratio of 4.17.

“The spontaneous seroclearance of HBeAg, HBV-DNA and HBsAg occurs consecutively in the natural history of chronic hepatitis B,” Chen said.

In the study, the researchers noted that this finding had significant clinical implications for the treatment of chronic HBV.

Other risk predictors for hepatocellular carcinoma (HCC) and cirrhosis are old age, male gender, alcohol consumption and a history of HCC, in addition to biological gradients of serum liver enzymes, HBV-DNA and antigen levels.

Chen said collaborative studies on external cohorts have corroborated the accuracy of the risk calculators for liver disease progression found in the REVEAL-HBV study.

“The estimated cumulative lifetime risk of cirrhosis and HCC in chronic HBV patients is 42 percent and 22 percent, [respectively],” Chen said. “HBV viral load is a major predictor for the spontaneous seroclearance of HBeAg.”

*REVEAL-HBV: Risk Evaluation of Viral Load Elevation and Associated Liver Disease/Cancer-HBV.