Differentiate those who are chronically infected, immune, or susceptible
The CDC recommends screening for both HBsAg and anti-HBs. Taken together, the results of these tests can help you discern if the patient is actively infected (HBsAg-positive); immune (HBsAg-negative and anti-HBs-positive); or susceptible (negative for both seromarkers).
Testing for the antibody to HBV core antigen (anti-HBc) is occasionally included in screening panels. Its presence cannot distinguish between current and previous infection. False-positive test results also occur.
Vaccinate seronegative individuals who are at risk for HBV
Although the CDC recommends vaccination of all HBsAg-negative individuals at risk for acquiring HBV, vaccine coverage of adults in the United States remains low.2,16 The workshop panel recommends that all primary care offices treating adults stock HBV vaccine. Of course, routinely stocking vaccine may present financial challenges, including purchase cost, storage, unused expired product, and reimbursement. Your practice may want to coordinate coverage with the local department of health, area hospitals, or large practices that stock vaccine, to ensure timely vaccination of patients.
No further follow-up is needed for patients immune to HBV
If the screening result for HBsAg is negative but anti-HBs is positive, the patient is immune to HBV. If the screening panel also included testing for anti-HBc and it is positive, the patient has natural immunity. A positive result for anti-HBs alone indicates prior vaccination or prior infection and seroconversion.
A positive HBsAg screening test calls for further patient work-up
If a patient tests positive for HBsAg, collect baseline data for ALT, HBeAg, anti-HBe, and HBV DNA levels.
In addition, encourage screening and vaccination of sexual partners and close household contacts of infected individuals. Patient education and counseling are important to dispel myths about HBV transmission (eg, HBV is not spread through casual contact such as handshakes or food sharing) and to reinforce the importance of regular care to prevent disease progression.
Evaluating and monitoring the chronic HBV patient
Use serum ALT levels, HBeAg and anti-HBe serology, and HBV DNA levels to identify the phase of HBV infection and guide patient management (FIGURE).
Interpreting viral DNA levels: Knowing when not to treat
The presence of HBeAg in serum indicates viral replication. Although HBeAg-positive patients in the immune tolerant or immune active phases generally have high levels of circulating HBV DNA (>20,000 IU/mL), these DNA levels do not necessarily correlate with active liver disease. In the immune tolerant phase, there is no clearly established benefit of antiviral treatment regardless of HBV DNA levels, and the risk of development of viral resistance to oral antiviral drugs is a serious concern. There is also no indication for treatment in the inactive carrier phase.
Discuss with patients why treatment is inappropriate in these phases and how the development of resistance to antiviral therapies can have serious negative consequences for their future treatment needs. Also explain that, because chronic HBV infection is dynamic, they will require lifetime follow-up care, even if they are currently in the immune tolerant or inactive phase.1,3
Surveillance for HCC in patients with chronic HBV infection
The most common adverse outcome of chronic HBV infection is HCC, occurring in up to 25% of men and 15% of women over their lifetimes.17 Because early detection and effective treatment for HCC can prolong life in HBsAg-positive individuals who have HCC or are at risk for acquiring it, the workshop panel recommends that primary care providers perform periodic screening for HCC according to the current AASLD guidelines.3,17 Candidates for HCC screening are those with family histories of HCC; those with cirrhosis or co-infection with HCV or HIV; and men >40 years and women >50 years. HBV-infected men born in Africa may acquire HCC at a younger age due to possible environmental exposure to aflatoxin, a carcinogenic mold. The AASLD guideline suggests screening this group with liver ultrasound every 6 months, starting at age 20. Although the AASLD guideline does not specifically recommend measuring serum alpha-fetoprotein (AFP), many practitioners monitor AFP, which improves sensitivity but has low specificity.17
Rising ALT suggests active liver disease
Serum ALT is a surrogate indicator of possible liver damage or disease. Generally, when an HBsAg-positive patient’s ALT rises above normal (≥19 IU/L for women and ≥30 IU/L for men, when standard reference ranges are 0-40), they have moved into the immune active phase, where liver inflammation and fibrosis can develop.
Also consider other potential causes of ALT elevation, especially when it occurs in association with low or undetectable levels of HBV DNA. Alternative causes include hepatitis C, heavy alcohol use, medications, and nonalcoholic fatty liver disease. Consultation with a liver specialist may be helpful to rule out or confirm these comorbidities.