Evaluation of Four Qualitative Third-Generation HIV Antibody Assays and the Fourth-Generation Abbott HIV Ag/Ab Combo Test

Objective: Compare the agreement between four third-generation rapid or automated human immunodeficiency virus (HIV) tests vs the fourth-generation Abbott ARCHITECT HIV Ag/Ab Combo assay (Combo Test) (Abbott Laboratories, Abbott Park, IL) in 7 clinical laboratories located throughout the Dallas-Fort Worth, TX, metroplex area. Methods: We tested a total of 220 specimens from the general population of patients being screened for HIV antibody status, including Western blot (WB) and HIV-1 RNA viral load by NAAT in patients with initially positive HIV screening tests. We performed a method precision study of the Combo Test and evaluated the agreement between the 4 comparative methods (CMs) against the Combo Test method (TM) using a 2 x 2 contingency table to determine values for positive percent agreement (PPA), negative percent agreement (NPA), and overall percent agreement (OPA) according to the guideline (EP12-A2) for the evaluation of qualitative assays published by the Clinical Laboratory Standards Institute (CLSI). Results: The Combo Test yielded consistent (reproducible) results when the HIV antibody (or p24 antigen) concentration was 20% away or more from C-50. In addition, values for PPA, NPA, and OPA for CM vs TM result's were all 100%, or not significantly different from 100%. Conclusion: The high detection rate of the Combo Test, when coupled with its high diagnostic sensitivity and specificity, rapid TAT (<30 minutes) of test results using a fully automated instrument (ARCHITECT), and excellent agreement with HIV-1/2 antibody results by several commercially available HIV-1/2 screening tests and with WB and NAAT results, indicate that the Abbott HIV-1/2 Ab/Ag Test is a useful screening test in the identification of HIV-infected individuals.