Comparison of PHA Method with EIA Quantitative Method for Anti-HBs Test

Shin, Bo Moon; Bae, Hyun Joo

Abstract

BACKGROUND: Hepatitis B surface Antibody(anti-HBs) is the marker of success of Hepatitis B virus(HBV) vaccination and protective ability against HBV infection. Though quantification of anti-HBs using EIA methods based on mIU/mL unit is available in these days, passive hemagglutination(PHA) is still one of the most popular methods to test Anti-HBs in Asian areas including Korea because of its simple procedure and inexpensive costs. However, we have not yet known the exact meanings of positive or negative PHA results compared with EIA results based on mIU/mL units. We evaluated the PHA method compared with EIA method using 856 specimens for testing anti-HBs.
METHODS
EIA measurements of anti-HBs were performed on an automated enzyme-immuno assay analyzer(Axsym, Abbott, USA). The Axsym is micro-particle EIA assay system and shows the test results as positive and negative according to the measured titer. The positive cut-off level of anti-HBs in Axsym is 10 mIU/mL. PHA measurements of anti-HBs were performed with manual microplate method(Fujirebio, Tokyo, Japan).
RESULTS
Regarded the EIA method as gold standard, the sensitivity and specificity of PHA were 83.2% and 95.5% respectively. The positive and negative predictive values of PHA were 98.1% and 66.9% respectively. The usual lowest detection level of PHA method for anti-HBs seemed to be from 50 to 100 mIU/mL.
CONCLUSIONS
Conclusively, we propose we should replace the PHA method with EIA method based on mIU/mL for testing anti-HBs regardless of costs. It is the way to save health cost associated with determination HBV vaccination or booster dose. It should be remarked in present that about 33% of anti-HBs negative cases with PHA method were adversely anti-HBs positive with titers of almost under 100 mIU/mL.