False-Positive Rate High for Rapid Oral HIV Test
Test assessed on patients seen in the emergency department
TUESDAY, Aug. 5 (HealthDay News) -- A rapid oral HIV test administered to patients in the emergency department has a high rate of false positives, according to study findings published in the Aug. 5 issue of the Annals of Internal Medicine.
Rochelle P. Walensky, M.D., and colleagues from Harvard Medical School in Boston, assessed the performance of a reactive rapid oral HIV test (Oraquick ADVANCE Rapid HIV-1/2 Antibody Test manufactured by OraSure Technologies of Bethlehem, Pa.) in 849 adults seen in the emergency department of Brigham and Women's Hospital in Boston.
The researchers found that 39 patients (4.6 percent) had positive results, of which five were confirmed to be infected with HIV (prevalence 0.6 percent), 26 were not infected with HIV, and eight declined confirmation, giving a specificity of 96.9 percent. For the unconfirmed cases, they estimated that the positive likelihood ratio was 8 to 32. Western blotting to detect HIV proteins was only able to conclusively determine HIV status in half of patients, while the addition of testing for HIV-1 RNA improved this detection rate to 96.2 percent, the report indicates.
"The unexpected high rate of false-positive results in Walensky and colleagues' study emphasizes that even HIV tests approved by the U.S. Food and Drug Administration may not do well in acute care settings," Christopher D. Pilcher, M.D., and C. Bradley Hare, M.D., from San Francisco General Hospital, write in an accompanying editorial.