What Does a Positive Rapid HIV Test Result Mean?
The accuracy of diagnostic tests is expressed in terms of sensitivity and specificity, as well as the positive and negative predictive value of the test result. No test is both 100% sensitive (no false-negative test results) and 100% specific (no false-positive test results). Screening tests are designed to be highly sensitive to ensure that no infected person is missed. The price for this high sensitivity is a slightly reduced specificity, that is, some women who are not infected with HIV will have false-positive HIV screening test results. In addition, the positive predictive value of a test depends on the prevalence of the condition in the group being screened. In a setting where prevalence is high, a positive result from a screening test is much more likely to reflect the persons true status than is a positive result in an area of low prevalence, where a higher percentage of positive results will be false-positives. In all settings, a positive rapid HIV test result is a preliminary
