Role of HBsAg Neutralisation Test in Low Positive and Indeterminate HBsAg Results by Electrochemiluminescence

Abstract

Hepatitis B surface antigen (HBsAg) is the important marker in diagnosis and decision making of Hepatitis B infection. Equivocal results are common diagnostic challenges with HBsAg. The study evaluates the role of neutralization assay in equivocal HBsAg results. Serum samples which documented equivocal or low positive COI where subjected to HBsAg neutralization assay. Percentage reduction in false positivity and recommended COI for deciding the assay was calculated. A subset of samples was subjected to molecular confirmation. Analysis of 51 samples showed 87.71% reduction in false positivity by using neutralization assay. 9.17 was the COI which showed highest AUC (0.702). Percentage positivity of molecular analysis of 13 samples was 70% (9/13). The optimum COI for utilizing neutralization assay is high from the study which is probably due to the high mean COI (12.1) of the included samples. Use of follow up HBsAg neutralization assay is recommended in equivocal HbsAg results to confirm the interpretation. However, the cut-off COI for implementation of test may vary for different population and analysers used for testing.

Keywords

• hepatitis b
• neutralization assay
• hbsag
• chemiluminescence
• cut-off index