To the Editor.
—In the study on the use of OMT for HIV antibody screening, Ms Gallo and coworkers1 conclude that the sensitivity of OMT testing is 99.9% and that the specificity is 99.9%. Unfortunately, neither of these numbers is accurate since the true prevalence of disease in this population is not known. For a large number of individuals included in this study, a confirmatory serum HIV antibody test was not done.Sensitivity is defined as the probability of a positive test when the disease is truly present.2 Defining a test as "sensitive" therefore assumes that all true positives have been identified. Usually this is done by comparing the new test to a "gold standard," which in this case should be serologic HIV testing. This criterion standard should be applied to all individuals tested, not just to a select subset. The authors include 2382 "low-risk" subjects (defined as those with an
Tessler LF, Walsh JME. Usefulness of Oral Mucosal Transudate for HIV Antibody Testing. JAMA. 1997;277(20):1591. doi:10.1001/jama.1997.03540440025015