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By: ELIZABETH WEILL-GREENBERG COMMENTS
 
Local health clinics are looking closely at HIV test results after clinics in California and New York received a high number of false positives with a widely used oral test.
The L.A. Gay & Lesbian Center and two San Francisco Department of Health testing sites stopped using OraQuick Advance, a mouth-swab test that delivers results in about 20 minutes. The L.A. Gay & Lesbian Center reported 13 false positives in November.
Twelve San Francisco Department of Public Health sites still use the OraQuick test, said Teri Dowling, the department's manager of HIV Counseling and Testing.
OraSure Technologies Inc., the Bethlehem, Pa.-based company that makes the OraQuick Advance tests, is working with testing sites, the CDC and the FDA to try to discover why the false positives are occurring in what appear to be geographical clusters.
"We are certainly taking seriously the recent reports from these clinical sites, and we have moved aggressively to systematically evaluate each situation," OraSure president Douglas A. Michels said in a statement. "Based on our investigation to date, we remain confident in the overall performance of the test."
Leo Rennie, bureau chief for HIV Prevention at the District's Administration for HIV Policy & Programs — formerly known as the D.C. HIV/AIDS Administration—said his office is reviewing all of the D.C.-area sites that have reported false positives.
So far, an internal review of some 12 to 15 clinics found that there are about two to five false positives out of 1,000 tests at each site. One site, which he declined to name, was outside that range.
The problem, Rennie said, appears to be localized to New York and parts of California.
"We have not experienced any rate of false positives that are outside the expected rate," agreed Kim Mills, spokesperson for Whitman-Walker Clinic in D.C.
Out of more than 9,000 tests performed in 2005 at sites in Virginia, Maryland and D.C., as well as in outreach vans, three were false positives, she said.
Those false positives occurred since July, which, she said, "raised questions in our eyes." The clinic is continuing to investigate the results, she said.
Kathie Hiers, chief executive officer of AIDS Alabama and co-chair of the Southern AIDS Coalition, said the organization has not had any problems with oral testing.
Health professionals routinely caution people to understand that the oral rapid test is a preliminary test that needs to be confirmed by a blood test.
Some sites in New York and California have started using a rapid blood prick test if a person receives a positive result from the oral test.
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| Douglas Michels, president and CEO of OraSure Technologies, maker of the OraQuick Advance, a rapid HIV antibody test, has said the company is aggressively investigating reports of false positive results but remains confident in the reliability of its product. (Photo by Jason DeCrow/AP) |
Most importantly, the professionals advise, make sure to get a blood test to confirm a positive result from the oral test.
"With any test, there are going to be false positives," said AIDS activist Larry Bryant, national field organizer for Housing Works in New York. "We don't want to give people a reason not to go and get tested."
The clusters of false positives are within FDA guidelines that allow for two false positives per 100 tests, according to Bernard Branson, associate director for lab and diagnostics at the CDC Division of HIV/AIDS Prevention.
It's important to look at the number of false positives over time, he said.
"It doesn't mean you get one [false positive] every 250 people," he said. "You may go through 2,000 people and have no false positives, then suddenly you have eight."
OraQuick allows for four false positives per 1,000, Branson said.
In New York, for example, about 4,000 tests are conducted each month, he said. In August and September, clinics in New York reported five false positives. In October, there were 11, and in November there were 35. But during four months, there was an average of 3.5 false positives per 1,000 tests, Branson said.
The higher number of false positives in New York may have been just a "blip," as the numbers are slowing down, he said.
So far, no problems have been reported with the blood-prick test, which also gives results in 20 minutes.
While the cause of the oral test's false positives is still being investigated, experts say it could be any number of factors including problems with the way the test was administered, a bad batch of tests, other substances present in the mouth, or environmental factors like at what temperature the test is stored.
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