Oral HIV Testmaker Addresses
False Results
Larry Buhl
PlanetOut Network
December 22, 2005
In response to growing concern over the accuracy of OraQuick Advance Rapid HIV antibody test, the test's manufacturer has begun its own investigation into a high number of false-positive results in three cities.
Early this month, the San Francisco Department of Health stopped using the popular test at its two clinics after a large number of positive results later turned out to be negative after using traditional screening methods.
Last week, the Los Angeles Gay & Lesbian Center discontinued use of the oral version of the rapid OraQuick HIV test after 13 people who took the oral test at the center falsely registered as HIV-positive. Health officials in New York are also monitoring a number of false positives, which shot up inexplicably in November, but they have not discontinued the test.
The test maker, OraSure Technologies, said Wednesday that it has initiated a "scientific and systematic evaluation of each situation" and is working in collaboration with affected customers, health care officials and government agencies, including the federal Centers for Disease Control and Prevention and Food and Drug Administration, to determine the causes for the unexpected results.
In addition, the company says it has been contacting customers throughout the country to learn if they are experiencing similar results with the test.
OraSure would not respond to requests for interviews, but encouraged people to learn more about the test at www.orasure.com.
The FDA approved the OraQuick Advance HIV test for professional use in March 2004. It is now used throughout the country as a first step to detect antibodies to the virus that causes AIDS. It uses fluid swabbed from the mouth and can produce results in 20 minutes.
OraSure has filed its intent to manufacture a home HIV test, but the approval process is in the preliminary stages, said Richard Klein, HIV/AIDS program director in the FDA office of special health issues. Klein told the PlanetOut Network that the irregularities found in test results in three cities are puzzling but not necessarily a reason to stop using the test.
"When the test was approved in 2004, it had a 98.6 percent specificity, which means you could expect about two false positives out of a thousand results," he said. "Now the results from Los Angeles and San Francisco are showing approximately nine false positives out of a thousand, which the FDA still considers good specificity."
No other HIV testing facilities outside New York, San Francisco and Los Angeles have yet reported a high rate of inconclusive or false-positive results. Health administrators who have stopped using the test say the results are not life-threatening, but that ongoing irregularities can cause people to question the accuracy of all HIV tests.
"If the public loses confidence in the reliability of HIV tests, they're just going to stop testing, and we can't allow that to happen" said Quentin O'Brien, director of health and mental health services at the Los Angeles Gay & Lesbian Center. He added that no irregularities have been reported with the rapid "finger-stick" test.
Klein contended that it is important for the company to find out why the test is coming back with an increased number of false positives, but also emphasized that users need to have a better understanding of the test's limitations.
"The oral antibody test is a screening test, not a confirmatory test," he said. "It is more sensitive than accurate, which means it can react to other antibodies that are similar to HIV. Clinics always need to confirm positive results with a more specific test like the Western Blot. So patients would end up waiting on those results regardless of which screening tool (oral or finger-stick) is used."
Klein added that it is too early to predict whether accuracy concerns will scuttle FDA approval of the test for home use.