Human Immunodeficiency Virus Rapid Antibody Tests
Following CDC guidelines, HIV antibody testing in the United States has traditionally followed a two-step process that begins with a screening enzyme-linked immunosorbent assay (EIA), followed by a confirmatory test, either a Western Blot or an indirect fluorescent antibody test (IFA). Final HIV antibody test results are discussed with the patient only after all testing has been completed. While this two-step process is very sensitive and specific, several days to weeks can elapse before results are available to discuss with the patient. During this interval, up to one third of patients are lost to follow-up. Rapid point of care testing permits immediate counseling and initiation of treatment.
Other situations where rapid testing is appropriate include testing of pregnant women that are admitted to labor and delivery with no prenatal care and health care workers who are exposed to HIV infected blood or body fluids. Rapid HIV antibody testing of a patient who is the source of a health care worker exposure allows for immediate prophylactic treatment with antiretroviral drugs.
The FDA has approved six rapid HIV antibody tests in the United States. All of the tests can be performed in less than thirty minutes. Four of the tests are immunochromatographic or lateral flow assays and two are enzyme linked immunoassays (ELISA). Most of the rapid tests detect antibody within 3 to 4 weeks after infection. Sensitivity ranges from 99.3 to 100% and specificity ranges from 99.1 to 100%. Rapid HIV tests performed on whole blood or oral fluid are classified as waived tests by CLIA, while those using serum or plasma are classified as moderately complex. Some of the tests detect HIV-1 and HIV-2, while others only detect HIV-1.
|
Test name |
Specimen |
HIV-2 detection |
|
Oraquick ADVANCE |
Oral fluid, whole blood, plasma |
Yes |
|
Uni-Gold Recombigen |
Whole blood, serum, plasma |
No |
|
Reveal G-3 Rapid |
Serum, plasma |
No |
|
Multispot |
Serum, plasma |
Yes |
|
Clearview STAT-PAK |
Whole blood, serum, plasma |
Yes |
|
Clearview COMPLETE |
Whole blood, serum, plasma |
Yes |
Rapid HIV test results should be confirmed with supplemental tests. Most laboratories repeat testing using a standard HIV antibody ELISA in duplicate followed by either Western Blot or an indirect immunofluorescence assay.
The major limitations of rapid HIV antibody tests include their higher cost per test and their higher false positive rate when testing pregnant women.
