Third- to Fourth-Generation HIV Testing: Reduction in False-Positive Results With the New Way of Testing, the Corporal Michael J. Crescenz Veteran Affairs Medical Center (CMCVAMC) Experience

• Published in: American journal of clinical pathology Vol. 150; no. suppl_1; pp. S70 - S71
• Main Authors: Dalal, Sharvari, Petersen, Jeffrey, Luta, David, Jhala, Darshana
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 21-09-2018
• Subjects: HIV; Human immunodeficiency virus; Laboratories; Patients; Quality assurance
• ISSN: 0002-9173; 1943-7722
• DOI: 10.1093/ajcp/aqy093.172

Abstract
Introduction
In 2006, the CDC issued guidelines advocating routine HIV screening of all patients. However, false-positive results are a potential patient care threat for low-risk populations even with very sensitive and specific assays. While confirmatory testing is needed, a reduction in HIV false-positive screening results can potentially be seen by switching (from the older third generation) to a more sensitive and specific fourth-generation screening assay. As this has not been published in the English literature for the veteran population to the authors’ knowledge, we studied the impact on the false-positive screening rate of a change to a fourth-generation assay at the CMCVAMC.
Methods
Quality assurance documents on test volume were reviewed to obtain the total number of HIV screening tests that were performed by the laboratory during March 1, 2016, to February 28, 2017, prior to implementation of the fourth-generation assay and the year afterward (March 1, 2017, to March 1, 2018). In addition, records of all positive screening results during those time periods were reviewed. The third-generation assay was the Ortho-Clinical Diagnostics Vitros (Raritan, NJ) and the fourth-generation assay was the Abbott Architect (Santa Clara, CA).
Results
Prior to implementation, there were a total of 7,529 HIV screening specimens; of those, 54 were reactive on the third-generation screening assay. On further review, 23 were true positives, 28 were false positives, and 3 were indeterminate. Afterward, there were 7,803 HIV screening specimens; of those, 27 were reactive on the fourth-generation screening assay. On further review, 17 were true positives and 10 were false positives.
Conclusions
There were fewer false-positive results with testing with the more specific fourth- vs third-generation assay (0.12% vs 0.37%, respectively). This reduction in false-positive screening has the potential to reduce laboratory workload with the necessary confirmatory testing.