To get back to the central question on this topic, and not simply trail off into flame wars, trolling and irrelevancy, there are three levels at which diagnostic criteria are important: 1) criteria used to form research cohorts, 2) clinical diagnosis and treatment, 3) disability claims. My concern is far from hypothetical. We have previous bad experience with problems in each, concerning diagnosis and exclusionary conditions. This works in both directions, with some researchers willing to exclude any physiological abnormality to promote their agenda, and others completely ignoring exclusionary criteria.
In the "Lipkin study" there was a kind of "Mexican stand-off" between factions with irreconcilable preconceptions, which removed about 85% of patients actually being treated for "CFS". This apparently included everyone who tested positive in the original Science paper being contested. In the study by Leonard Jason, testing the "empirical definition", this swelled the cohort created by those criteria so that it was dominated by patients with a primary depressive disorder. If you wait to treat ME/CFS until you have "the answer" to all depressive disorders you are going to wait a very long time. Depressed patients may well have problems with a physiological basis, (I would guess this already applies to 10%) which is complicated by secondary depression, but that is not the best cohort to use if you really want to understand etiology. The existence of a subset of patients without secondary depression ought to be welcomed as a chance to make progress in a field virtually without much useful progress for ages.
In the PACE trial researchers achieved the impossible by having it both ways. They excluded the vast majority of patients who were referred to them as "CFS patients", while apparently performing no clinical testing to find biological exclusionary conditions. This was necessary to accomplish both stated and unstated economic goals. Had the cost of any testing been included their economic claims would have fallen completely flat. To keep costs down you need to avoid both high treatment costs and high testing costs needed to exclude patients who might actually die as a result of misdiagnosis. (Simple examples: subclinical myocarditis, Lyme disease, various autoimmune disorders, various endocrine disorders, various neurological diseases of unknown etiology, early stages of any number of cancers. Did any of those "CFS" patients have a thorough cardiological, neurological, endocrinological or rheumatological work up? )
Both the U.S. HHS and the U.K. NHS+DWP are extremely worried about a flood of disability claims, and under orders to hold the line on rising costs, particularly if we are talking about long-term disability of mysterious origin. This is perhaps the major factor in institutional inertia preventing research progress. If you can't even consider the question of organic disease in research without being struck by lightning bolts you certainly will never resolve these questions. Quite a number of people who are not suffering at present, and are drawing paychecks, find the current impasse quite tolerable.
When it comes to advice actually useful in clinical practice, we have a serious problem of not having any cure to recommend, falling back on symptom relief which would presumably take place in the absence of a clear diagnosis. As I've already stated on this topic, we can find many practicing doctors who will interpret each of the proposed diagnostic criteria in ways at odds with those considered by the current report. Changing ideas "based on vast clinical experience" will not be easy. Nor is there any diplomatic way of telling practicing doctors much experience is only "half-vast", being derived by repeating the same mistakes over time.
