Natural History of Chronic Hepatitis B – Clinical Implications

Worldwide, between 350 and 400 million persons are estimated to be chronically infected with hepatitis B virus (HBV) and 15% to 40% of those persons are at risk of developing cirrhosis and/or hepatocellular carcinoma (HCC) without intervention.[1] High and intermediate rates of HBV prevalence, defined as > 8% and 2% to 8%, respectively, of hepatitis B surface antigen (HBsAg), the marker for active infection, are found in all of the continents of Asia, the South Pacific and Africa, much of Eastern Europe, the Amazon region of South America, several Mediterranean countries, the Caribbean, and indigenous populations of the Arctic, New Zealand, and Australia.[2] Persons who are born in one of these regions and who immigrate to the United States or Western Europe should be screened for HBV markers. Recently, a double-blind, placebo-controlled trial involving 651 persons from Taiwan who had cirrhosis showed that lamivudine, a nucleoside analog that inhibits the reverse transcriptase activity of HBV, significantly reduced the rate of death from liver disease and HCC.[3] The medications currently approved by the US Food and Drug Administration (FDA) for the treatment of hepatitis B include interferon alfa-2b, pegylated interferon alfa-2a, and the oral nucleoside/nucleotide analogs lamivudine, adefovir, entecavir, and telbivudine. Two other medications, tenofovir and emtricitabine, already approved for the treatment of HIV infection, also demonstrate activity against HBV.[4] This article explores the natural history of HBV, with a focus on how to best select those individuals who might be candidates for treatment.