3. Promoting HIV Testing in Diverse Populations
Point-of-Care Testing vs Laboratory-Based Testing
Most available HIV tests detect only antibodies to HIV, which, in most newly infected persons, develop and become detectable using current testing technologies at an average of at least 2 weeks following infection. [Bennett]
During acute HIV infection,
antibodies have not yet developed, and the only tests that can be used during that period are ones that are designed to detect evidence of the virus itself.
Most HIV testing programs offer either one of 2 types of testing: point-of-care or laboratory-based. [Modica C. 2009] With point-of-care tests, the practitioner take a specimen from the patient—either oral fluid or blood—and has the test performed.
With an oral fluid test, the specimen is inserted into a developing fluid, with results available in approximately 20 minutes. Specimens for such tests are simpler to collect and are more readily accepted by most patients. [White 2009]
Point-of-care blood-based tests use either a finger prick or whole-blood sample produce results in 10 to 20 minutes. Currently, 4 point-of-care HIV tests—each highly sensitive and specific—have been approved for marketing (Table-I). [FDA list 2011]
However, in light of the extensive implications of a positive HIV test finding, the results found with a single specimen—whether that is performed at point of care or in a laboratory—must be confirmed, generally by sending the specimen to a laboratory for further evaluation and confirmation, typically by a Western blot assay. In the case of HIV tests that are initially performed in a laboratory setting, however, performance of confirmatory testing typically is done automatically without the need for submission of a second specimen from the patient.
Either of 2 different technologies is typically employed to perform laboratory-based HIV testing [Bennett]:
- The more common one is an enzyme-linked immunosorbent assay (ELISA). Because most laboratories conduct this type of assay in batches only once a day or every few days, results are often not available for several days.
- Multiplatform devices, a more recent technology, run specimens continuously and can produce results in approximately an hour; some of these devices are also able to detect HIV antigen. Multiplatform devices are increasingly being employed in larger testing facilities.
