Roche Amplicor 1.5 versus Chiron bDNA
Oct 20, 2004
Doctor: I tested positive about five years ago. I've been on meds for a bit over three years now, and suffice to say I'm in very good shape, overall. My issue for much of the past three years, however, has been an inability to consistently reach the holy grail of 'below 50 copies' on viral load. I've gotten there several times, but after a reading of <50, it then might blip to, say, 419, and then, amonth later, to 582, then back to <50, then to 934, then <50, etc. Of course my Dr. - an HIV specialist here in NYC that I have 110% faith in - has been very frustrated by this, and has switched the combos I've been on for the past 3 years, to try to reach the magic <50 VL on a consistent basis. My Dr. has now come to realize though, after talking with many other doctors around the country, that there seems to be a significant difference in the main tests that are used to determine VL. The test that was being used for all of my tests - except for the past two - was the Roche Amplicor 1.5. For my last two tests, the Chiron bDNA test was used and, indeed, my last two tests came back at <50 (which has happened only once in 3 years of testing). My Dr. has said many doctors he has spoken with have had this same experience (i.e, many of their clients were not <50 on the Roche test, but, when tested with the Chiron test, were <50). Do you know of any 'scuttlebutt' on this? And is there one test out there that is becoming the standard? It seems alarming to me that treatment decisions are being made based on a test that may not be accurate. Thanks for your time - we all appreciate it.
Response from Dr. Henry
The Chiron test and Roche test use different technologies so there are often mild differences. I used to use the Chiron test but now use the Roche test exclusively. Switching back and forth will lead to lots of differences like you describe. It is my experience that the Roche test may be a little more sensitive at the low end. Recently we have had a frustrating increase in the number of low level RNA levels with the Roche test due to a change in the type of tube the lab recommended to use. That says that the test is not perfect and has to be interpreted with common sense and experience added in. Switching back and forth between assays is not recommended in most situations since conflicting results are bound to be found and not easy to resolve. KH
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