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

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. 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 × 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). The Combo Test yielded consistent (reproducible) results when the HIV antibody (or p24 antigen) concentration was 20% away or more from C^sub 50^. In addition, values for PPA, NPA, and OPA for CM vs TM results were all 100%, or not significantly different from 100%. The high detection rate of the Combo Test, when coupled with its high diagnostic sensitivity and specificity, rapid TAT (