Performance characteristics of a rapid HIV antibody assay in a hospital with a high prevalence of HIV infection

Background: The delay between collection of blood samples and availability of test results may be as long as 3 weeks and is one barrier to the acceptance of voluntary testing for human immunodeficiency virus (HIV) infection. Serologic tests that provide results rapidly could overcome this barrier, but the accuracy and reliability of rapid tests have not been well characterized in the United States. Objective: To evaluate, in a ''real world'' setting, the performance characteristics of a rapid HIV assay that reduces the need for patients to return for counseling after the test. Design: Testing of HIV antibodies by rapid and nonrapid assays and survey about risk behaviors for HIV. Setting: A hospital in Bronx, New York, with a high prevalence of HIV-seropositive patients. Patients: 837 patients who were not known to be infected with HIV, had not been admitted for conditions related to the acquired immunodeficiency syndrome, and agreed to participate in HIV testing and an interview. Measurements: Sensitivity and specificity of a rapid HIV antibody assay based on comparisons with nonrapid assay and Western blot assay. Results: According to nonrapid assays, 5.4% of patients were infected with HIV. The rapid assay was highly accurate in this sample overall: Its sensitivity was 1.00, its specificity was 0.991, its positive predictive value was 0.865, and its negative predictive value was 1.00. The assay was also highly accurate in various subgroups. Conclusions: Accurate, rapid tests for HIV infection may enhance testing programs by preventing the need for delayed counseling of seronegative patients and by providing preliminary results to seropositive patients. These preliminary results may encourage patients to return for confirmatory test results and to adopt risk-reducing behaviors sooner.