| Kevin Delaney, MPH Epidemiologist, Diagnostic Applications, Behavioral and Clinical Surveillance Branch, CDC |
| Issue: Rapid testing for HIV provides two distinct advantages over traditional HIV testing: the ability to provide immediate results, and the ability to take testing and a test result to people and places that were previously inaccessible. Despite the fact that all FDA approved rapid test package inserts contain language stating that: “This test is suitable for use in multi-test algorithms designed for statistical validation of rapid HIV test results. When multiple rapid HIV tests are available, this test should be used in appropriate multi-test algorithms,” rapid HIV tests are currently only being used as single screening tests which require confirmation by either Western Blot or IFA. |
| Description: In this study, persons seeking HIV testing at a high prevalence STD clinic in Los Angeles, CA were simultaneously tested with several HIV rapid tests. Additionally both serum and plasma specimens were collected and tested with a traditional EIA and Western blot. Results of individual rapid tests and combinations of rapid tests used in sequence were compared to the results of the EIA and Western blot testing. |
| Lessons Learned: Nearly all individual rapid test results (13102/13129=99.8%) agreed with the results of the serum EIA and Western blot. Sensitivity of all rapid tests was greater than 98%, with nearly all falsely negative specimens coming from clients known to be HIV positive and on treatment. Adding a second, different rapid test resulted in 100% specificity for specimens that were reactive on both rapid tests, with between 0 and 4 specimens being discordant and requiring a third “tie-breaker” rapid test. The average cost of a second rapid test was approximately half the cost of a Western blot, suggesting significant cost savings are possible. A limitation of this study is the lack of follow-up information on persons with one or more positive rapid tests whose confirmatory test was negative or indeterminate. |
| Recommendations: Rapid test only algorithms for the diagnosis of HIV infection can be as sensitive and specific as the current diagnostic algorithm. A rapid test algorithm has the additional advantage of providing same day, point of care diagnosis of HIV infection. Given the current trend towards using a rapid test to screen for HIV infection, rapid test only algorithms also could provide significant cost savings over traditional confirmatory testing (Western Blot). Further investigations which demonstrate the use of a rapid test only diagnostic algorithm at the point of care are warranted. Such investigations should include follow-up of anyone testing positive on one or more rapid tests whose confirmatory Western blot is either negative or indeterminate. |
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Last Update: April 8, 2005 |