Rapid Diagnostic Testing for HIV:
Clinical Implications of a New Diagnostic Tool

Antibody testing to diagnose HIV was introduced in 1985.⁸ At that time, most testing was performed in large laboratories equipped with highly trained technologists who performed testing in batch assays. Such an approach allowed facilities to develop effective labor-saving quality control techniques while insuring the reliable performance of tests, but it also led to infrequent testing and long turn-around-times. The standard laboratory HIV testing protocol involved multiple steps with varying delays at each step along the way:

1. Specimen procurement via phlebotomy.
2. Transportation to a central laboratory.
3. Assay specimens utilizing EIA or IFA.
4. Enzyme Immunoassay screening procedure performed by trained medical technologists.
   • If POSITIVE → Repeat, then perform a confirmatory test (Western Blot or IFA) if repeatedly reactive.
   • If NEGATIVE → Generate a report.
5. Report generation and review by the laboratory director.
6. Transmittal to the patient’s physician or HIV counselor.
7. Result review with the patient.

From a technical perspective these procedures were very sensitive and quite specific.

The lag time between obtaining a specimen and providing results is a time of high anxiety and significant stress for many patients. While the time to perform an HIV antibody test is typically a few hours, the time required by the testing paradigm was typically multiple days to two or more weeks. Such long delays and the accompanying anxiety clearly contributed to the nearly 30% of patients who failed to return to State counseling centers for their results.

Rapid HIV diagnosis began to assume particular importance as effective, combination antiretroviral therapy became available. Combination therapy is more effective when given immediately following exposure to HIV and it clearly reduces the risk of vertical and occupational HIV transmission while improving the quality of life and the longevity of people infected with HIV disease.

Significant reduction in the lag time between risk exposure and the availability of testing results required the evolution of a new approach to HIV testing – the rapid HIV test. These tests are widely available internationally, including six that have been approved by the United States Food and Drug Administration (FDA). The recent introduction of Clinical Laboratory Improvement Act (CLIA) waived HIV rapid test kits has allowed widespread availability of point-of-care (POCT) HIV testing with turn-around-times of 20 to 40 minutes.

Integration of rapid HIV testing into daily practice at the point-of-care allows prompt diagnosis of patients with HIV disease. These patients can then be referred to a provider with experience and expertise treating HIV patients. In addition, these patients can be referred for prevention and social services. More detailed information on the clinical aspects of rapid HIV testing is included in the first part of this article, “Rapid Diagnostic HIV Testing: Clinical Implications.”