Myalgic Encephalomyelitis has been classified by the World Health Organisation as a neurological disease (ICD – G93.3) since 1969. Originally called ME and defined by Dr Ramsay the term chronic fatigue syndrome or CFS was introduced and the definition watered down to fatigue lasting 6 months or more. There are now more than 20 diagnostic definitions of CFS being used by different researchers in different countries, and the illness ME has been lost within them.
A recent definition and yet another name change to SEID (Systemic Exertion Intolerance Disease), was established after the 2015 Institute Of Medicine’s (IOM now called National Academy of Medicine NAM) review in the US. This was intended to be used as a diagnostic tool, however it has been used in research even though it has never been validated and this study shows that it is likely to include people with primary depression (the same issue we have had with other criteria for CFS most notably the Oxford criteria used in the PACE trial). The study concludes that SEID is a questionable discriminant tool because of this.
In 2011 a group of 25 experienced international researchers and clinicians with experience of treating more than 50,000 patients had already volunteered their time (unsponsored) to properly define the illness based on biomedical research and clinical experience to produce the International Consensus Criteria (ICC). See here for the full paper Carruthers_et_al-2011-Journal_of_Internal_Medicine. Most patients agree that this is a good definition of the illness and most importantly it gets rid of the 6 month waiting time before diagnosis is made. It is very important for ME patients that the illness is diagnosed as soon as possible since early rest and treatment has a large impact on its future path. It is crucial not to over do things in the early stages so as to prevent a significant worsening.
Using more than one definition of the illness is holding back research and confuses results that may or may not be useful. The ME Patient Foundation believe ICC to be the most useful criteria for research and diagnosis.