Application of sequential serological testing strategy for detection of Hepatitis B surface antigen (HBsAg) for diagnosing HBV infection.

The diagnostic accuracy of any serological test for detection of HBsAg is not 100%. We hypothesized that the sequential testing strategy proven for anti-HIV laboratory diagnosis should also apply to other infectious disease markers like HBsAg. Therefore, we evaluated the diagnostic accuracy of these strategies, I (single test), II (two tests in sequence), III (three tests in sequence) for diagnosis in patients and blood donors and compared it to the confirmatory test for HBsAg (Neutralization Test). Samples were initially tested for HBsAg by A1- Enhanced Chemiluminescent Immuno Assay (ECLIA). Initial reactive (aliquoted donor/patient) samples were reflexly tested by A2- Enzyme Linked Fluorescence Assay (ELFA) and A3- Immuno Chromatography Assay (ICA) assays. Confirmatory neutralization assay was performed on all initial reactive samples. Four strategies (I, II A, II B, and III) that were used in this analysis were; I = A1, IIA = A1 + A2, IIB = A1 + A3, and III = A1 + A2 + A3. The results of all four strategies were compared to Gold Standard (Neutralization Test). A total of, 112, 011 blood samples (75,111 patient samples and 36,900 whole blood donor samples) were initially tested for HBsAg by A-1 (CLIA). Amongst the tested samples, 1,296, 1,188, 1,078, 1,074 samples were found to be reactive by strategy I, IIA, IIB, III respectively. We observed that the PPV (Positive Predictive Value) of Strategy III > Strategy IIB > Strategy IIA > Strategy I. Sequential serological testing strategy comprising of initial sensitive test followed by more specific test increases the diagnostic accuracy of test report as compared to a single test.