December 9, 2005
According to San Francisco Department of Public Health officials, analyses of more than 6,000 rapid-result oral HIV tests conducted in city public health clinics since spring found 47 positive results in patients who were negative in follow-up testing. Of the roughly 200 positives detected by the OraQuick Advance HIV test, one out of four was wrong, said Dr. Jeffrey Klausner, the city's director of STD prevention and control services. He said there have been no known cases of negative results in patients later found to be positive, which would be much more dangerous.
The Food and Drug Administration approved the test for professional use in March 2004 and is considering an application by its maker, Orasure Technologies, to allow over-the-counter sales.
Klausner said City Clinic, the department's main site for STD and HIV testing, no longer uses the oral test, though he added, "I am not ready to discard this citywide."
Joanna Rinaldi, deputy director of the AIDS Health Project in San Francisco, said her program stopped using the oral test three weeks ago after logging 28 false positives since the spring. "We just couldn't have more folks be distressed," she said, noting there have been no more false positives since AHP returned to finger-stick blood testing.
In response to the problem, the California Department of Health Services is conducting a statewide survey. While the problem has not yet turned up in other cities, results from Los Angeles are not in. San Francisco has forwarded its findings to CDC, Orasure and the state Office of AIDS.
"We have not lost confidence in the test, but we still have to be vigilant about it," said Deanne Sykes, a research scientist for the state Office of AIDS. She does not believe the problem stems from how San Francisco clinicians are conducting the test, as they are among the world's most experienced HIV testers. One theory is that there is something about the San Francisco patients -- perhaps a high prevalence of hepatitis -- that causes a "cross reaction" with the HIV test.
Orasure CEO Douglas Michels expressed "every confidence that the test is reliable and accurate" and said no similar problems have been reported outside San Francisco.