Globally, chronic hepatitis B virus (HBV) infection is the leading cause of liver-related morbidity and mortality. Worldwide, more than 2 billion people have been exposed to HBV, and about 250 million are chronically infected. 1
The prevalence of hepatitis B surface antigen (HBsAg), the serologic marker of chronicity, varies significantly worldwide. The highest rates of HBsAg are reported in Asia, Sub-Saharan Africa, and the Amazon basin. The overall prevalence of chronic HBV infection in the U.S. is low, 800,000 to 1.4 million persons. The disease is predominantly seen in immigrants, with > 90% of cases in persons from countries of intermediate or high HBV prevalence, such as East Asia, Africa, Pacific Islands, parts of Africa, and Eastern Europe. 2
The prevalence of chronic HBV infection in the U.S. may be underestimated and closer to 2.2 million persons, because many foreign-born persons are generally excluded from national prevalence surveys. 3 More worrisome, studies suggest that a majority of individuals with chronic HBV infection are unaware of their diagnosis, and consequently, many patients who might benefit from therapy do not receive appropriate care or treatment. 4 This review will discuss screening recommendations for HBV in the U.S., identify knowledge gaps regarding the disease, and present a cogent argument for why treatment-eligible patients should be entered into management programs and evaluated for therapy.
Hepatitis B Screening
Chronic hepatitis B meets the criteria established by the World Health Organization as a disease for which screening would be beneficial to public health. Chronic HBV infection is an important health problem that can result in serious sequelae, such as cirrhosis, hepatocellular carcinoma, and liver-related mortality. Moreover, persons unaware of their diagnosis may unwittingly transmit the virus to unprotected individuals.
A simple, relatively inexpensive test is widely available to identify chronic HBV infection. The test allows physicians to confirm a diagnosis before symptoms develop and offer a safe and effective therapy. Modeling studies suggest that screening populations with a prevalence of chronic HBV infection ≥ 2% also would be cost-effective in reducing the burden of HBV-associated liver cancer and chronic liver disease in high-risk populations.5,6 However, a number of barriers exist that limit screening (Table 1).
Who to Screen?
All guidelines recommend that persons at high risk for HBV infection should be screened. Broadly, these include persons from geographic areas with a high prevalence of chronic infection, persons at high risk for acquiring HBV infection, persons with increased risk of transmitting HBV, and persons at risk for reactivation of HBV. In addition to previous recommendations, the Centers for Disease Control and Prevention (CDC) updated 2008 guidelines now recommend testing all persons born in geographic areas with a HBsAg prevalence of ≥ 2%, U.S.-born persons not vaccinated as infants whose parents were born in regions with HBsAg prevalence ≥ 8%, persons who inject drugs, men who have sex with men, persons with elevated alanine transaminase and aspartate transaminase of unknown etiology, and persons with selected medical conditions that require immunosuppressive therapy (Table 2). 7 In 2014, the U.S. Preventive Services Task Force provided updated guidance on screening of nonpregnant adolescents and adults that aligned with the CDC guidelines and also recommended screening individuals at high risk for HBV infection. 8 The American Association for the Study of Liver Diseases and other professional liver organizations support these recommendations. 9