Point-of-Care Tests for Hepatitis B: An Overview

Abstract

Despite the heavy disease burden posed by hepatitis B, around 90% of people living with hepatitis B are not diagnosed globally. Many of the affected populations still have limited or no access to essential blood tests for hepatitis B. Compared to conventional blood tests which heavily rely on centralised laboratory facilities, point-of-care testing for hepatitis B has the potential to broaden testing access in low-resource settings and to engage hard-to-reach populations. Few hepatitis B point-of-care tests have been ratified for clinical use by international and regional regulatory bodies, and countries have been slow to adopt point-of-care testing into hepatitis B programs. This review presents currently available point-of-care tests for hepatitis B and their roles in the care cascade, reviewing evidence for testing performance, utility, acceptability, costs and cost-effectiveness when integrated into hepatitis B diagnosis and monitoring programs. We further discuss challenges and future directions in aspects of technology, implementation, and regulation when adopting point-of-care testing in hepatitis B programs.

Keywords: hepatitis B; hepatitis elimination; point-of-care testing; public health.

Figure 1

Cascade of care for hepatitis B and laboratory-based tests required for standard of care. Laboratory-based blood tests are required at every stage of the hepatitis B cascade of care for diagnosis, assessment of liver disease stage, treatment eligibility and long-term monitoring of disease progression. Diagnostic testing for hepatitis B involves detection of hepatitis B surface antigen (HBsAg) in blood, which indicates active infection with the virus. Standard laboratory electro-chemiluminescence immunoassay-based HBsAg testing is performed on serum or plasma samples derived from whole blood. If active infection is confirmed, subsequent blood tests are performed to determine the stage of disease and need for treatment, including a hepatitis B virus (HBV) polymerase chain reaction (PCR)-based quantitative DNA level or viral load, a hepatitis B eAg and eAb assay and liver function tests to determine whether an elevated aminotransferase (ALT) indicative of liver inflammation or other signs of impaired liver function are present. Further assessment for the presence of liver fibrosis and cirrhosis is also required, most commonly by transient elastography and/or liver biopsy. All patients irrespective of treatment require ongoing disease monitoring, including at minimum an HBV DNA level, HBeAg and HBeAb (if not already seroconverted from HBeAg positive to HBeAb positive) and ALT levels every 3–6 months.

Figure 2

Natural history and clinical characteristics of the phases of chronic hepatitis B infection. Current international hepatitis B management guidelines have different criteria for initiating hepatitis B treatment; however, all restrict nucleos(t)ide therapy to those with at least moderate liver fibrosis and/or inflammation and a high viral load.