RESUMEN
BACKGROUND: The specificity of HBsAg enzyme immunoassay (EIA) has been previously reported between 95% and 100% for blood donor screening in Korea. Considering that Korea is highly endemic in HBV infection, it is highly recommended that blood donors showing true positive for HBsAg were permanently deferred from donation. Identification of false-positive results by a confirmation assay would be a necessary step for this purpose. This study was intended to evaluate LG HBsAg Confirm (LG Chemicals Corp., Seoul, Korea) kit as a confirmation test and know the positive predictive value for HBsAg screening results. METHODS: LG HBsAg Confirm reactivities were evaluated in 279 patients and 185 blood donor samples, all of which were positive in HBsAg EIA. Patients samples were positive in both HBsAg EIA and HBV DNA. Confirm positive was determined according to the following 2 step criteria: (1) the percent neutralization is 50% or more (first-step neutralization), or (2) if not, the percent neutralization after 1:1,000 dilution of original sample is 50% or more (second-step neutralization). RESULTS: LG HBsAg Confirm kit confirmed all 279 patients~ sera as positive. All of 185 blood donor samples showed true positive results. First-step neutralization confirmed 157 sera (33.8%) as positive and second-step neutralization confirmed 307 sera (66.2%) among 464 samples. CONCLUSION: Performance of LG HBsAg Confirm was so excellent that all the samples showing positive in both HBsAg EIA and HBV DNA tests could be determined as confirm positive.