Fatigue: the tip of the diagnostic iceberg

For many of us, getting an accurate diagnosis of CFS / CFIDS / M.E. is a time-consuming, difficult and yes, fatiguing process.

Proper diagnosis of CFS / CFIDS / M.E. requires comparing a patient's symptoms with the health condition's accepted case definition and excluding other illnesses with similar symptoms. And by excluding, I mean using illness-specific criteria that don't include everything but the kitchen sink. The looser the diagnostic categorization the more likely the misdiagnosis of this bio-medical neurological disorder.

Let's start with fatigue. You can't get much looser than the term "fatigue". The word fatigue in our society is applied to anything from the delicious tiredness that comes from a day full of active fun to the profound, bone-crushing exhaustion caused by serious illness. In the medical sense, fatigue is measured by persistence and pattern. Undifferentiated, the medical symptom, fatigue, is common to many grave and not-so-grave illnesses. Without differentiation, the term is diagnostically useless.

A good example of this is the Oxford Criteria of CFS, developed in 1991 by British psychiatrists Simon Wessely and Michael Sharpe. The Oxford Criteria defined CFS as a "syndrome in which fatigue has been present for at least six months, during which time it has been present more than 50 percent of the time". By simply requiring prolonged fatigue for a CFS diagnosis, the Oxford Criteria allowed a broad variety of psychiatric illnesses to qualify as CFS and supported the premise of the authors that CFS is actually mass hysteria resulting from a personality disorder and can be treated with a program of graded exercise.

No wonder the Oxford Criteria has yet to be medically validated more than a decade later and has since been superceded by more refined definitions as the biological evidence piles up.

As Susan Sontag notes, "...Theories that diseases [illnesses] are caused by mental states...are always an index of how much is not understood about the physical terrain of a disease.....".

In 1994, a new criteria was drawn up by the U.S. Center for Disease Control 1994 CDC / Fukuda CFS Criteria. This definition included the earlier requirement of the presence of new-onset fatigue lasting at least six months, but it went a step further by also requiring the presence of at least four of eight other physical symptoms. "A case of the chronic fatigue syndrome is defined by the presence of the following: 1) clinically evaluated, unexplained persistent or relapsing chronic fatigue that is of new or definite onset (has not been lifelong); is not the result of ongoing exertion; is not substantially alleviated by rest; and results in substantial reduction in previous levels of occupational, educational, social, or personal activities; and 2) the concurrent occurrence of four or more of the following symptoms, all of which must have persisted or recurred during six or more consecutive months of illness and must not have predated the fatigue: self-reported impairment in short-term memory or concentration severe enough to cause substantial reduction in previous levels of occupational, educational, social, or personal activities; sore throat; tender cervical or axillary lymph nodes; muscle pain; multijoint pain without joint swelling or redness; headaches of a new type, pattern, or severity; unrefreshing sleep; and postexertional malaise lasting more than 24 hours."

Although more narrowly defined than the extremely loose Oxford criteria, the optionality of other cardinal physical symptoms of CFS kept the diagnosis focused on the broad and imprecise symptom of fatigue, distorting the overall biological pattern of this neurological disorder. The 1994 Fukada criteria, superceding the even vaguer 1991 Oxford Criteria, was intended to make sure researchers were testing the same populations; but as a precise diagnostic tool it remained tantamount to driving a finishing nail with a sledge hammer.

Enter the 2003 Canadian CFS/ME Clinical Working Case Definition. Developed by an international CFS team of treating physicians, teaching faculty and researchers this 2003 definition is "real world" and reflects an on-going accumulation of biological research and evidence. As the authors of the Canadian report write, "The panel felt there was a need for the criteria to encompass more symptoms in order to reflect ME/CFS as a distinct entity and distinguish it from other clinical entities that have overlapping symptoms. As fatigue is an integral part of many illnesses, the panel concurred that more of the prominent symptoms should be compulsory."

What does this mean in terms of creating a new standard for clinical diagnoses? Well, first off it defines "fatigue" more precisely. CFS/ME is now more narrowly defined by post-exertional fatigue. The difference? Unlike fatigue from which people recover, post-exertional fatigue is pathologically delayed recovery. While fewer patients may meet this criteria, the chances of being misdiagnosed are significantly less.

The 2003 Canadian Definition also states that cardinal symptoms are no longer optional and that patients must have neurological / immune and/or neuroendocrine manifestations such as orthostatic intolerance, vertigo, loss of thermostatic stability, and worsening of symptoms with stress. Finally, with the 2003 Canadian Definition a precise biological pattern is being constructed, and as the criteria becomes more stringent, fewer people are being misdiagnosed.

Thankfully we have evolved far beyond the earlier definition of CFS as simply involving vaguely defined fatigue. Yes, the fatigue those of us with CFS experience is horrific, and is not to be belittled. But as the sole diagnostic criteria it is not enough, not by a long shot.

Note: Marilyn Kerr, RN writes about the importance of diagnostic codes, not only for diagnostic purposes, but to accurately and effectively document patient statistics. The article was written in 2001 and thus does not include the latest changes. Kerr also refers to fibromyalgia, which is further clarified by Margaret Williams in 2004. More on ICD diagnostic codes can be found at http://virtualhometown.com/dfwcfids/cfids/classified.html.

Psychiatric footnote from Kate:

It should also be noted that the World Health Organization 1992  ICD-10 index and subsequent revision code CFS/ME "chronic fatigue syndrome" at G93.3 in the chapter on the nervous system and the category "other diseases of the brain," specifically forbidding its categorization under F48.0.This is a huge change from the ICD 9 classification system drawn up in 1975 by the World Health Organization (WHO) which, allowed CFS/ME to be listed as the equivalent of nueresthenia at F48.0 in the category "neurasthenia," a designation which specifically excludes code G93.3 illnesses.

On 23rd January 2004, Andre l'Hours from the WHO headquarters provided the following clarification (in writing):

"This is to confirm that according to the taxonomic principles governing the Tenth Revision of the World Health Organization's International Statistical Classification of Diseases and Related Health Problems (ICD-10), it is not permitted for the same condition to be classified to more than one rubric as this would mean that the individual categories and subcategories were no longer mutually exclusive".

l'Hours  also confirmed that the

ICD classifications (for ME/CFS) are approved by the World Health Assembly and therefore take legal precedence over *unapproved modifications* made by a WHO Collaborating Centre.

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The Collaborating Centre making these unapproved modifications is based at King's College UK. Home of Professor Wessely and the psychiatric lobby.

ME/CFS are both classified by the WHO Headquarters in Geneva as diseases of the central nervous system and not under mental and behavioural disorders (F48.0) as has been incorrectly stated and promulgated by WHO Collaborating   Centre, King's College UK.