Figure 1: HIV Testing in the Laboratory (Standard) Setting versus POC Setting
HIV Testing - Standard: In the Laboratory Setting
STEP ONE:
Standard HIV testing is offered in healthcare venues such as clinics, physician offices, and hospitals. Pre-test counselling is provided to the patient and then a venous blood sample is collected and sent to an approved medical laboratory with a requisition ordering an HIV test.
STEP TWO:
A) The blood sample is screened using an enzyme immuno assay (EIA) (although some laboratories use a newer test known as chemiluminescent microparticle immuno assay). These tests will generate either a “reactive” or “non-reactive” (negative) finding. Test results can also be “indeterminate”, which are treated as “reactive” for the purpose of this algorithm. A reactive finding is not necessarily an HIV-positive diagnosis; a reactive finding requires that the blood sample be retested to rule out or confirm a positive HIV diagnosis.
B) Non-reactive findings are considered negative and test results are provided to the patient. No further action is required.
STEP THREE
Reactive and indeterminate samples from Step 2A are retested. Non-reactive results are treated the same as in Step 2B. A second reactive or indeterminate result requires the sample to go to Step 4.
STEP FOUR
Reactive and indeterminate samples undergo a more sensitive confirmatory test known as the Western Blot assay. As with previous steps, the western blot assay can result in a reactive, non-reactive or indeterminate result. Non-reactive results are addressed as described in Step 2B. Reactive or indeterminate results are addressed in Step Five.
STEP FIVE
Reactive (HIV-positive) and indeterminate test results are provided to the patient along with post-test counselling. Those testing indeterminate are encouraged to be re-tested.
HIV Testing - In the Point-of-Care Setting
STEP ONE:
Point of care testing is offered on-site in healthcare venues such as clinics, physician offices and hospitals. Test results are available in about one minute, so a combined pre- and post-test counselling session is provided. Most commonly, fingerstick blood or a saliva sample is used, depending on the test kit.
STEP TWO:
A) The blood or saliva sample is tested using the kit which will generate either a “reactive” or “non-reactive” (negative) finding. Test results can also be “indeterminate”, which are treated as “reactive” for the purpose of this algorithm. A reactive finding is not necessarily an HIV-positive diagnosis; a venous blood sample needs to be collected so that confirmatory testing can be done as described in Step Three.
B) Non-reactive findings are considered negative and test results are provided to the patient. No further action is required.
STEP THREE:
The reactive or indeterminate results are shared with the patient. A venous blood sample is obtained to rule out or confirm a positive HIV diagnosis.
STEP FOUR:
The venous blood sample undergoes a confirmatory test known as the Western Blot assay. Some labs may test the sample using the full standard protocol. As with previous steps, the western blot assay can result in a reactive, non-reactive or indeterminate result. Non-reactive results are addressed as described in Step 2B. Reactive or indeterminate results are addressed in Step Five.
STEP FIVE
Reactive (HIV-positive) and indeterminate test results are provided to the patient along with post-test counselling. Those testing indeterminate are encouraged to be re-tested.