SUMMARIES FOR PATIENTS
Rapid Oral Testing for HIV Infection
5 August 2008 | Volume 149 Issue 3 | Page I-30
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The summary below is from the full report titled "Revising Expectations from Rapid HIV Tests in the Emergency Department." It is in the 5 August 2008 issue of Annals of Internal Medicine (volume 149, pages 153-160). The authors are R.P. Walensky, C. Arbelaez, W.M. Reichmann, R.M. Walls, J.N. Katz, B.L. Block, M. Dooley, A. Hetland, S. Kimmel, J.D. Solomon, and E. Losina.
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What is the problem and what is known about it so far?
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Human immunodeficiency virus (HIV) is the cause of AIDS, an illness that interferes with the body's ability to fight infection and some types of cancer. Treatments containing several drugs have improved outcomes for HIV-infected patients. The spread of HIV is from person-to-person contact with blood or other body fluids that contain the virus. People can have HIV infection for years before becoming sick.
Many experts recommend screening adolescents and adults for HIV infection. "Screening" means testing people for infection who feel well rather than waiting until symptoms develop. Early detection is important because persons who know they have HIV can avoid doing things that put others at risk for becoming infected. Their doctors can monitor them for declining immune function and start antiviral treatment before trouble with infections occurs. In the past, most testing for HIV infection involved 1 or more blood tests. Obtaining results of these tests sometimes took many days. Recently, several rapid oral tests for HIV have been developed. Few studies have examined, however, whether these rapid oral HIV tests can correctly identify people with HIV infection.
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Why did the researchers do this particular study?
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To see whether a rapid oral HIV test (OraQuick, OraSure Technologies, Bethlehem, Pennsylvania), done in the emergency department, correctly identifies adults with HIV infection.
849 adults without known HIV infection who visited a Boston emergency department in 2007. The average patient age was about 37 years, about 35% were men, and 20% were black.
Researchers recruited adults without known HIV disease who attended a large, urban emergency department. None of the patients had indicators of urgent life-threatening or severe emergencies. Researchers collected oral samples from the patients and sent the samples to the emergency department laboratory. The tests were read within 20 to 40 minutes. If results were negative, patients received no further testing for HIV. If results were reactive (positive), patients had multiple blood tests to confirm HIV infection. These tests included a serum enzyme-linked immunoassay, a single serum Western blot test, CD4 count, and plasma HIV-1 RNA measurement. Results of the confirmatory tests were not available the day of the emergency department visit. The researchers then examined the number of patients who had both reactive results and confirmed HIV infection.
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What did the researchers find?
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39 of the 849 adults who attended the emergency department had a reactive rapid oral HIV test. Confirmatory tests showed that 5 of the 39 patients were HIV-infected. This means that the prevalence of HIV infection in this population was 0.6%. The specificity of the oral test in this setting was 96.9% (95% CI, 95.7% to 98.1%). Specificity is the proportion of true-negative results that are correctly identified by the test.
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What were the limitations of the study?
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The study involved a single urban emergency department. Test sensitivity was not assessed because patients with nonreactive results did not receive confirmatory tests.
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What are the implications of the study?
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Rapid oral HIV testing can help identify patients with increased odds of HIV infection. In settings in which HIV prevalence is low, however, most reactive oral test results will be proved to be false-positive by additional testing.
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