How reliable are the PCR and the bDNA tests?
Dec 19, 1996
The PCR and the bDNA tests are being used more often today, especially the bDNA test. Mr. Sowadsky, do you know how reliable these two tests are? I mean what is the false negative rate of them? Currenty is there any HIV infection due to different strains that would only be picked up by the ELISA and Western but not the two DNA tests?
Response from Mr. Sowadsky
Hi. Thank you for your question.
There can be a wide degree of variance of the accuracy of these diagnostic tests for HIV infection. In labs that have a lot of experience with these tests, they are highly accurate tests. However, because they are very difficult tests for labs to perform, they are more likely to have false positive and false negative readings, as compared to the standard antibody tests. Because of potential false readings on these tests, they are usually done more than once, or are done in conjunction with other diagnostic tests for HIV. These tests should pick up the vast majority of strains of HIV, as is the case with the antibody tests.
I have enclosed an abstract of a recent journal article that reviews the accuracy of PCR diagnostic testing. Although it's quite technical in nature, note the conclusion:
"The PCR assay is not sufficiently accurate to be used for the diagnosis of HIV infection without confirmation. Use of PCR for the diagnosis of HIV in adults should be limited to situations in which antibody tests are known to be insufficient. "
So, in summary, although these tests are getting better, they do not replace the use of antibody tests in the vast majority of circumstances, for HIV testing in adults.
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