What is the significance of the reported increases in false positives when using the oral fluid HIV test in New York City sexually transmitted disease (STD) clinics?
It is important to keep in mind that overall oral fluid tests have performed well. The significance of the increase in false-positive oral fluid test results is not yet known. However, when the accuracy of a test varies like this in one site it is necessary to determine if it is a temporary event a site-specific issue, or a change in the way the test is working. A false-positive HIV test result is an emotional event for patients that can create anxiety over one's health and mistrust of the medical system. From a provider's standpoint, a pattern of increased false-positive test results from a specific test may create less confidence in the test and add more costs for confirmatory testing.
The increase reported in NYC STD clinics represents <1 percent of all reactive oral fluid rapid tests. From March 2005, when NYC DOHMH, began using oral fluid rapid testing, through May 2008, 0.27% (or 442) of the 166,058 oral fluid rapid HIV tests were false-positive with peaks in late 2005 and between November 2007 and April 2008. Despite these episodic elevated levels of false positive results, the oral fluid test has always performed above the Food and Drug Administration's minimum threshold of 98.0% specificity.
CDC is committed to ensuring patients get correct test results. Further investigation is needed into the NYC DOHMH experience; but it is critical to know that the oral fluid test followed by a confirmatory test, results in an accurate diagnosis and has shown success in reaching more people for testing. The first step to helping to ensure improved health for those infected and to help prevent transmission of HIV to others is knowing one's HIV infection status.