|Do you answer tough questions?
Jun 1, 2007
non-approval by the CDC, not a diagnostic test, false positive and $$s.
Please Check: a)http://www.cdc.gov/hiv/topics/testing/resources/qa/be_tested.htm#wait b)http://www.hivtest.org/subindex.cfm?fuseaction=faq#8
Concerns: 1. 'a' clearly mentions that RNA PCR is a diagnostic test and has a window period of 12 days after the exposure, I got it at the 13th day and it turned out negative (less than 50 copies).
2. 'b' says lately PCRs have been approved by the CDC.
I will test at the appropriate time with an antibody test to back my PCR result. I had a condom breakage exposure, pulled out as soon as I realized it broke :(
Do you think, I can rely on this test?
I'd be very grateful to you, long live Dr.Bob !
| Response from Dr. Frascino
This continues to be a confusing point for many folks (doctors included!). Part of the problem is that our understanding of HIV, the body's immune response to HIV infection and our testing techniques all continue to evolve. Addressing your specific questions, here's the way I view the current situation:
1. The HIV RNA PCR test has a false-positive rate of 2% to 9%, usually at low titer (i.e. less than 10,000 copies per ml). The sensitivity of this test depends on the viral load and the threshold of the specific assay. Results can also be affected by use of antiretroviral therapy. Sensitivity does approach 100% with untreated acute HIV infection. The specificity is 97% overall, but approaches 100% with viral loads of greater than 10,000 copies per ml. Therefore you can see there are technical aspects of this test that can affect results. It is a very useful test for monitoring HIV disease and, in particular, the response to HAART (antiretroviral therapy). Because of the technical considerations, cost and false-positive rate, I do not feel this test should be used for routine HIV screening. You can read many testimonials in the archives where folks obtained this test (inappropriately in my opinion) and got a positive result, which ultimately was determined to be a false-positive. This, as you will read, caused an incredible amount of anxiety.
2. Yes, HIV PCRs have been CDC approved but not for routine HIV screening! As indicated above, we use these tests for other purposes. For instance, DNA PCR tests can be helpful in sorting out disputed or indeterminate serological tests.
So can you rely on this test? In my opinion your test results are extremely encouraging. However, since you are trying to apply test results to an indication for which this test was never intended, I cannot advise on its reliability. I agree with your decision to take the appropriate test (HIV antibody test) at the appropriate time (after the three-month window) to obtain a definitive, conclusive and reliable result!
Finally, what do you mean "Do you answer tough questions?" I don't find this question at all tough, but rather just mildly confusing to the overly anxious and uninformed. Do I answer tough questions? Yes, of course!
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