Part of the task assigned to the IOM was to distinguish between subgroups, which they were unable to do: In achieving the first part of their task - recommending clinical diagnostic criteria for ME/CFS - PEM became mandatory, where as under Fukuda it had been optional. Therefore, intentionally or inadvertently, the committee did subgroup. This is the result: Fukuda patients without PEM do not have ME/CFS (SEID). Fukuda patients with PEM are likely to have ME/CFS (SEID). In effect, what they have is what many of us (but not all) would already have understood by ME but with simplified criteria. Note that this does not automatically imply a single disease. Obviously we can only speculate about this but do you think it was an intentional act by the committee, to ditch a portion of the original group of patients? Ditch is a harsh word, I know. Have the committee done a favour to people without PEM? If they are fortunate, they will be medically reassessed and this may lead to the diagnosis of hitherto missed conditions. If they are unfortunate, they'll be treated to the same contempt that they currently 'enjoy'. Will they end up being stigmatised even by us? (See how easy it is to slip into 'them' and 'us' language? It's a painful thought.) The recommendation to make PEM mandatory is what many patients have been asking for. The 2 day CPET already provides evidence for PEM and no doubt biomarkers will follow. ME/CFS (SEID) must surely now be accepted as a serious, life altering / life demolishing disease with a biological basis. Given this and the under-diagnosis that the committee highlighted, increased research activity must follow. Somebody reassure me about that, please! What implications might the new clinical criteria have on research if any? Does anyone think this is now the end of the story as far as subgroups within ME/CFS (SEID) are concerned? Does it still make sense to include non PEM Fukuda type patients, who don't have an alternative diagnosis, as a discrete group within research of ME/CFS (SEID)?