Rapid HIV Tests

“In late 2005, an unexpected increase in the number of false-positive oral fluid tests occurred, but the increase subsided after several months. In December 2005, while the cluster of false-positive oral fluid test results was being investigated, the NYC DOHMH Bureau of STD Control suspended oral fluid testing in the clinics for 3 weeks…In late 2007, another larger increase in the incidence of false-positive oral fluid rapid test results was observed. The cause for the episodic increases in false-positive oral fluid tests has not yet been determined.”

“A recent surge in false positive results produced by a much-heralded oral HIV test has caused at least six testing sites in Los Angeles, San Francisco and New York to shelve the test and prompted an inquiry by federal health agencies”

“All reactive rapid HIV test results require confirmatory testing. CDC…protocols recommend 1) confirmation of all reactive rapid HIV test results with either Western blot (WB) or immunofluorescent assay (IFA), even if an enzyme immunoassay (EIA) screening test is negative, and 2) follow-up testing for persons with negative or indeterminate confirmatory test results, with a blood specimen collected 4 weeks after the initial reactive rapid test result. [this introduces two biases in favor of positive test results. A single negative ELISA is normally considered to be a true negative and a second round of confirmatory testing gives another chance for a positive confirmatory test, without a similar chance when the first confirmatory test is positive]”

“LIMITATIONS OF THE TEST…6. Limited studies were conducted to determine the potential effect of interfering substances and unrelated medical conditions on the performance of the Reveal™ Rapid HIV -1 Antibody Test. 7. The specificity of the Reveal™ Rapid HIV -1 Antibody Test for serum specimens in low -risk populations has not been evaluated. 8. Limited studies were conducted to determine the performance of the Reveal™ Rapid HIV -1 Antibody Test on fresh serum and plasma specimens. 9. A Reactive test result using the Reveal™ Rapid HIV -1 Antibody Test suggests the presence of anti-HIV-1 antibodies in the specimen. The Reveal™ Rapid HIV -1 Antibody Test is intended to be used as an aid in the diagnosis of infection with HIV -1. AIDS and AIDS-related conditions are clinical syndromes and their diagnosis can only be established clinically. Results of the MedMira Reveal™ Rapid HIV -1 Antibody Test should not be used in isolation, but in conjunction with the clinical status, history, and risk factors of the individual being tested. 10. The intensity of the red dot (Reac tive test result) does not necessarily correlate with the antibody titre [amount] of the specimen.”

“[After a positive OraSure rapid test result] With blood specimens, enzyme immunoassay (EIA) screening tests prior to the Western blot or IFA confirmatory test are optional. If an EIA is performed, even if it is non-reactive, the specimen must proceed to Western blot or IFA testing (reactive EIA specimens will automatically be tested by Western blot or IFA). For oral fluid testing, both EIA and Western blot testing should be performed to confirm results.”

“Of the 456 samples tested, HIV-antibodies were unequivocally detected in 21 samples (4.6%) by the Testpack…17 other Testpack results (3.7%) could have been considered to be positive, that is, false positive (negative in Western Blot). Usually the color-development, positive as well as negative reaction, is completed within 10-15 seconds, which is much less than the recommended two minutes. But in these 17 cases a faint vertical bar occurred beside the strong horizontal ("negative") bar after a period of 1-2 minutes. In this way of reading a HIV-positive result may be suggested. However, these results were considered to be HIV-negative, which was confirmed by Western Blot…In our opinion, a number of 3.7% inconclusive and potentially false positive Testpack results (as well as 3.1% in ELISA) is acceptable, since the consequence of false positive or inconclusive results in autopsies would lead only to special precautions of the medical staff [unless the death was claimed by some to be due to deliberate or negligent infection, in which case false positive results could have very important ramifications!]”