As many are aware, Labcorp will no longer allow physicians to order Western Blots for Lyme disease. The only test available is the ELISA with reflex to Western Blot if positive.
They have also taken away the C6 peptide. The results are presented as only negative if less than 0.91.
These changes are not going to get Labcorp any more business. What motivated the change?
One can only guess that someone affiliated with the IDSA influenced the policy change. In the past, when the Western Blot was ordered, the laboratory informed us the ELISA test should be ordered as well. Should be? According to whom?
Some ID doctors are inappropriately applying the HIV testing paradigm in the case of Lyme testing. When testing for HIV it is crucial to do the ELISA first because it is possible to have a positive Western Blot and a negative ELISA rendering a negative test. Luckily with HIV there are other, better, confirmatory tests available.
There is no evidence the same applies with Lyme testing. The IDSA has claimed there are a lot of false positive Lyme Western Blots because of cross reactivity. This claim remains largely unreferenced. I recently saw a patient with a history of syphilis, RPR positive. The Lyme Western Blot was entirely negative. Many patients test positive for rheumatoid arthritis and Epstein Barr Virus and have negative Western Blots. (these are the common scenarios said to cause false positive tests). The ELISA is known to have many false negatives. Skipping this test and going to the Western Blot increases the sensitivity of the test. If there is some decrease in specificity it would seem to be minimal at best. In other words, patients are more likely to get an accurate result when the physician orders the Western Blot directly and skips the ELISA.
The CDC still states that Western Blot testing should only be done when the ELISA is first positive. The Website states that IgM results found after the first 4-6 weeks are likely false positive unless 5/10 IgG bands appears at that time. These facts are referenced back to findings from 1994-95. As you may recall this finding was based on an assay using the discarded N40 strain of Lyme and B31 has become the standard strain.
1) These results are based on a meeting which occurred 20 years ago. When the testing remains so controversial why hasn't there been a more recent reassessment?
2) At best this is revisionist history. The test was developed for surveillance (an epidemiology or research tool) not for diagnosis. How a test developed for an entirely different purpose (monitoring the relative number of cases in different locations over time) morphed into a bullet proof test for diagnosis of Lyme disease is far beyond my ability to comprehend.
Why are we going backwards. Why is there a problem with giving physicians and their patients more information?
The CDC stubbornly says on their website that there are no borderline positive tests. There is an absolute requirement to have 5/10 bands because at least this many always shows up. According to the logic presented by the CDC the finding of a positive ELISA followed by the appearance of 4 IgG Western Blot bands is absolutely, 100% negative for Lyme.
One would like to know who wrote this tripe.
The long arm of the IDSA has managed to promote its agenda by manipulating the CDC and now Labcorp.
I caught Ben Beard, the chief of the bacteria section (Lyme included) of vector borne diseases for CDC off balance when I had the opportunity to meet with him along with members of Nat Cap Lyme some years ago. Dr. Beard was flustered when I pointed out the contradictions in the CDC pronouncements especially about the appropriate use of the two tiered Lyme test.
When I asked him if the CDC wasn't speaking out of both sides of its mouth on the topic he hemmed and hawed and then ultimately responded "well, that's the party line."
What party was he referring to? Democrats? Republicans? Perhaps the IDSA vs ILADS. Dr. Beard's s comment to me was an admission that politics have trumped reason, logic and science. The IDSA has extended its mandate. They are no longer a professional society for infectious disease physicians. They are in fact a political party. Triumphantly they can say, Labcorp: Welcome to the party! As with all political parties, the truth is frequently abandoned when its application leads to undesired results.
In the wake of emerging science and changes in the very nature of the pathogens responsible for Lyme disease this discussion is becoming more and more a moot point.
Its a win for: Quest, Clongen, IgeneX, Stony Brook and a few others. Lyme patients who are insured by health insurance companies that insist Labcorp be used should complain and lobby for a change to another lab. As they say: vote with your feet.