"Well-Characerized" When I was reading the comments in Science, I was struck by a term--"well-characterized"--that was used to describe the negative papers' cohorts. From the comment by van der Meer et al: From the comment by Lloyd et al: I think the reason I noticed this adjective is because it's one that Dr. Vernon applied several times to those cohorts in her February response to the Dutch study. She wrote, What I don't understand is why these authors believe patients diagnosed by the Oxford Criteria or Fukuda alone are better-characterized than those diagnosed by the Canadian Consensus Criteria, as those in the original Science paper were. (Yes, the Science cohort also met Fukuda because the CCC are a subset of Fukuda with PEM, but that's beside the point.) Leonard Jason has argued that the CCC select patients who are more functionally impaired, probably in part because they require patients to have PEM, which he has found is both sensitive and specific for ME/CFS. In fact, he advised the CAA to require its BioBank donors to have PEM, which is optional for Fukuda. (Oxford, of course, doesn't need it for diagnosis, either.) Even if Lombardi et al had not laid out additional characteristics of the original 101--which they did, in the Oct. 9 supplement--the Science cohort is by definition a narrower, more select, better-characterized group than the European cohorts because it meets the CCC. How anyone can argue otherwise is beyond me.