The problem for me is that many ME-patients testing positive for lyme via arminlabs, will not have lyme. As Edwards points out, the clinical picture is currently the best biomarker when it comes to lyme disease. Starting long antibiotics-treatment based solely on the result from a armin lab test, when one might have ME, is risky.
I agree it is likely that many patients tested positive for Borrelia by Arminlabs may not be infected with this bacterium (they will have false positive test results).
Although whether this is a good or bad thing is a matter of debate, because when you have a test like the Borrelia one, which is significantly less than 100% accurate in terms of sensitivity, and imperfect in specificity as well, you are going to get some false negatives and some false positives.
Remember that:
False negative = someone with a Borrelia infection, which the testing lab has incorrectly determined to be Borrelia-negative.
False positive = someone without a Borrelia infection, which the testing lab has incorrectly determined to be Borrelia-postive.
In all imperfect tests like the Borrelia test, the testing lab can play about with the numerical threshold for whether a patient is classed as positive or negative on the test. By playing about with the threshold, you can decrease the amount of false negatives the lab gets,
but at the expense of increasing the amount of false positives. Or you can set the threshold to decrease the amount of false positives the lab gets,
but at the expense of increasing the amount of false negatives.
With Arminlabs, Dr Armin Schwarzbach may have just set the threshold of his tests to reduce the number of people that get a false negatives on his tests (ie, people who have Borrelia, but are incorrectly tested negative, so will miss out on the benefits of antibiotic treatment); but that of necessity will mean that he is going to get more false positives (ie, people who do not have Borrelia, but are incorrectly tested as positive, so will get antibiotic treatment when they do not need it).
But the issue here is to try to evaluate the pros and cons of having less false negatives at the expense of more false positives (or vice versa). This is what setting your test's threshold is all about.
Every false negative means a Lyme patient misses out on treatment. Every false positive means someone without Lyme gets antibiotics when they do not need them (though provided the antibiotics used are well tolerated and with a low incidence of side effects, that may not be problem medically, but will be an unnecessary medical expense; although it will be a problem in the sense that if the patient thinks they have Lyme even though they don't, they may stop searching for other causes of their symptoms).
So the issue here to set the threshold for a positive test result in such a way that you try to avoid as many false negatives as possible, but without then having an inordinate number of false positives as a consequence. Different Borrelia testing labs will likely have different views on where to set the threshold, and I think Arminlabs probably sets the threshold to try to minimize false negatives, which means Arminlabs will have higher rates of false positives.
Whereas other more conservative labs may set the threshold to try to avoid an inordinate number of false positives, but as a consequence will get more false negatives.