Need for Confirmatory Neutralization Tests for Hepatitis B Surface Antigen Tests in Populations with Intermediate Prevalence

Abstract

Objective: Hepatitis B surface antigen (HBsAg) is known as the hallmark of hepatitis B virus (HBV) infection. This study aimed to determine whether an HBsAg neutralization test is necessary to accurately interpret HBsAg test results.

Methods: Initially reactive HBsAg specimens from a 5-year period, with cutoff index values between 1.0 and 2.0, were subjected to neutralization confirmatory testing using an Elecsys HBsAg Confirmatory test kit (Roche Diagnostics GmbH. Mannheim, Germany).

Results: The neutralization test showed 46.1% positive (confirmed positive group) and 53.9% negative (confirmed negative group) results from the total specimens. Among the confirmed negative group, 79.5% of patients were confirmed to be negative for the current infection, whereas 4 patients in the chronic hepatitis B subgroup showed a neutralization percentage close to 40%. More than half of patients in the confirmed positive group were considered to be in the hepatitis B e antigen-negative inactive HBsAg carrier phase.

Conclusion: In populations with intermediate HBV prevalence, a neutralization test is necessary to confirm an HBsAg result and reduce the false positive and false negative rates of initial HBsAg tests.

Keywords: HBsAg test; confirmatory assay; false positivity; immunology; inactive carrier; neutralization test.