The problem here would be the same as always: Against what value do you define high accuracy of disease? Every criteria is 100% accurate against itself and we don't know any diseases processes as of yet.
I would say the gold standard is diagnosis by expert clinicians. We know from a couple of studies that half of GP diagnoses are wrong – and almost all cases because that had been other, undiagnosed diseases (mostly biomedical, but also psychological) that explain the symptoms.
I suspect the specific criteria are less important, so long as we have Pem. (I'll be interesting to see, though, how.DecodeME cases would stack up against expert diagnosis as they, probably uniquely, have a decent definition of PEM, which does seem to be a very unusual symptom).
By expert clinicians, I mean those who are very familiar with the illness, and I will resource. The two papers that found about 50% of GP diagnosis were were led by Julian Newton and Peter White respectively. Plus, I think they had bigger teams for this to do a good job.
GP's unfamiliar with the illness and often dismiss it. Even specialist clinics are frequently held up by lack of resources, or by impeded by beliefs.
I believe that DecodeME is the best large cohort we have available, and the best possible job that could be done.
But it would still miss cases where there are undiagnosed alternative diagnosis. That's why I think it's use of a good pen question is so important.
