EVALUATION OF A QUALITY ASSURANCE PROGRAM FOR QUANTITATION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 RNA IN PLASMA BY THE AIDS CLINICAL-TRIALSGROUP VIROLOGY LABORATORIES

A number of quantitative assays have been developed by using amplifica tion techniques to measure human immunodeficiency virus type 1 RNA in the plasma of infected individuals. The Virology Committee of the AIDS Clinical Trials Group in the Division of AIDS, National Institute of Allergy and Infectious Diseases, has established a quality assurance p rogram (QAP) for quantitative assays of HIV-1 RNA levels in plasma. Th e primary objective of the QAP was to ascertain that a laboratory coul d maintain the precision required to have a 90% power to detect a five fold difference in RNA copy number between two samples in the same bat ch. To achieve this goal, the QAP required an intra-assay standard dev iation of no greater than 0.15 log(10) RNA copies per ml. Panels for p roficiency testing consisted of coded replicate samples and a common s et of standards. To date, 41 laboratories have participated in the pro gram and have used both commercial and in-house assays. We demonstrate d that 65% of the laboratories were capable of attaining the necessary level of intra-assay precision. The fitted regressions indicated that the differences among laboratories that used the same kit were genera lly greater than the differences among population-average regressions for the kits themselves. The use of an external QAP and a common set o f standards reduced differences both among laboratories that used the same kit and among laboratories that used different kits. Thus, use of a common set of standards across clinical trial protocols would allow for cross-protocol comparisons.