AEGiS-13CROI [34LBb]: Investigation of Reports of Excessive False-positive Oral Fluid Rapid HIV Tests

13th Conference on Retroviruses and Opportunistic Infections

Denver, Colorado - February 5-8, 2006

INVESTIGATION OF REPORTS OF EXCESSIVE FALSE-POSITIVE ORAL FLUID RAPID HIV TESTS

Conf Retrovir Opportunistic Infect 2006 Feb 5-8;13:abstract no. 34LBb

Bernard Branson¹, L Wesolowski¹, K Delaney¹, M Mavinkurve², T Dowling³, and D Mackellar¹
¹CDC, Atlanta, GA, US; ²New York City Dept of Hlth and Mental Hygiene, NY, US; and ³San Francisco Dept of Publ Hlth, CA, US

BACKGROUND: In March 2004, the FDA approved the OraQuick Advance HIV 1/2 Rapid Antibody Test for use with oral fluids. In December 2005, media reports about high rates of false-positive (FP) oral fluid tests in New York City (NYC) and San Francisco (SF) raised questions about the test’s accuracy.

METHODS: CDC investigated OraQuick performance using the following data sources: (1) 4 studies conducted between 2000 and 2005 in diverse populations in which the test was performed on whole blood and oral fluid collected simultaneously and compared with EIA/Western blot results; (2) post-marketing surveillance conducted from August 2004 to June 2005 at 368 testing sites in 14 states and 3 cities (project areas); and (3), from testing of oral fluid specimens conducted September to November 2005 in NYC and SF test sites.

RESULTS: Of 12,010 HIV-negative persons tested in the 4 studies combined, OraQuick specificity was 99.9% (95% CI: 99.8-100) with whole blood and 99.6% (95% CI: 99.4-99.7) with oral fluid; serum EIA specificity was 99.7% (95% CI: 99.6-99.8). In post-marketing surveillance, median specificity for the 17 project areas was 99.98% (range 99.7-100) for 134,247 whole blood tests and 99.90 (range 99.4-100) for 25,614 oral fluid tests. Excess FPs were observed at 3 sites in NYC and 1 site in SF but not at 18 other sites in the same cities using the same test kit lots.

	NYC - 3 sites with excess FP			NYC -7 sites without excess FP
	# tests	# false pos	Specificity	# tests	# false pos	Specificity
Sept	1662	4	99.8%	2316	2	99.9%
Oct	1762	10	99.4%	2279	1	99.9%
Nov	1581	32	98.0%	2164	3	99.9%

	SF - 1 site with excess FP			SF - 11 sites without excess FP
	# tests	# false pos	Specificity	# tests	# false pos	Specificity
Sept	232	8	96.5%	472	1	99.8%
Oct	262	9	96.5%	587	3	99.5%
Nov	160	6	96.3%	551	5	99.1%

CONCLUSIONS: Specificity of the OraQuick test is slightly lower with oral fluid than with whole blood, but still well above the FDA’s minimum threshold of 98% for rapid HIV tests. Investigation continues to identify site-specific factors that may lead to more FP oral fluid test results than expected.

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2006-02-05
34LBb

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