Differing case Definitions of CFS
What seems to be repeatedly overlooked is that the case definitions of ME and CFS are different and are formally recognised by the WHO as being different: ME is unequivocally classified under Disorders of the Nervous System (11) whereas fatigue states are classified under Behavioural and Mental (neurotic) disorders (12) . Moreover the WHO formally classifies fibromyalgia as a soft tissue disorder under "Rheumatism"; (13) fibromyalgia overlaps with but is different from ME.
Importantly, the Oxford 1991 case definition (14) and the US Centers for Disease Control 1994 case definition of CFS (15) do not specifically require the presence of physical signs, whereas the case definition of ME specifically includes observable, reproducible neurological disturbance. (16)
To confuse matters even further, the more strictly-defined American CFS studies (where ME/CFS is also known as chronic fatigue and immune dysfunction syndrome or CFIDS) almost certainly contain a sub-group of patients with the illness known to British and Australasian non-psychiatrist researchers as ME. There are currently ten different case definitions and it is now a well-acknowledged problem that different researchers (particularly certain UK psychiatrists) have been using their own case definitions and have been studying quite different patient populations but have been claiming that their results are universally applicable to all categories of chronic fatigue including CFS and ME. The Report of The National Task Force specifically highlighted this problem.
Despite the enormous body of published research which indicates that ME(or "CFS" under the strictest definition) is a physical disorder, nothing seems to modify the beliefs of these psychiatrists who hold that patients are merely experiencing an " exaggerated self-awareness of every physical feeling, to the point where symptoms become distorted ". They entirely dismiss "new research ideas" relating to the immunological and virological research findings which do not accord with their own beliefs. There is no acknowledgment of the evidence of abnormalities on brain scans which are consistent with infection. They misrepresent and trivialise the disorder, and there is no acknowledgment of the existence of sub-groups. They contend that patients have unhelpful illness beliefs.
Despite their views, the report to the Chief Medical Officer of England in 2002 gave an authoritative statement that ME/CFS " …is a genuine illness and imposes a substantial burden on the health of the UK population. Improvement of health and social care for people affected by the condition is an urgent challenge….Patients, their carers, and healthcare professionals encounter different levels and varying manifestations of disbelief and prejudice against people affected by the condition. " (17)