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At this time, there is no accepted conclusive test or series of tests of chronic fatigue syndrome. CFS is therefore largely an exclusionary diagnosis. If a doctor suspects a patient may have CFS they should begin the diagnostic process by eliminating other potential causes of the patient's symptoms. "Chronic fatigue" and similar symptoms can be caused by a wide variety of conditions which should be investigated, although treatment of the patient's symptoms can begin before a complete diagnosis is made. Subsequently tests should be run to exclude other abnormalities in the immune and central nervous system that cause the same or similar symptoms as seen in CFS patients.
CDC 1994 criteria (aka "Fukuda")
According to the 1994 CDC, a diagnosis of CFS requires that the following conditions be met (otherwise, the diagnosis is idiopathic chronic fatigue).
Primary symptom: incapacitating fatigue
Incapacitating fatigue that is:
* of new or definite onset (not since birth)
* unexplained by other medical cause,
* lasts for at least six months (from onset, not necessarily from when the patient becomes aware that the fatigue is an ongoing symptom)
* and is not improved by rest.
Additional symptoms
The fatigue must be accompanied by a minimum of 4 of the following eight symptoms:
1. Impairment of short-term memory and concentration
2. Sore throat
3. Tender lymph nodes
4. Muscle pain
5. Multi-joint pain
6. Headaches of a new type, pattern, or severity
7. Unrefreshing sleep or insomnia
8. Post-exertional malaise (fatigue lasting more than 24 hours after exertion)
Other systems
Other scoring systems have also been proposed to quantify CFS symptoms for research purposes. These include:
* Holmes et al (1988) scoring system. Also sometimes called "CDC 1988," to distinguish from the newer CDC system.
* Oxford criteria (1991)
* Carruthers et al (2003) Canadian Case definition for ME/CFS
* Australian Guidelines (2004)
Other ability/disability scales designed for similar symptoms to those of CFS have also been used.
Issues with the definitions/criteria
Several studies suggest that using different case definitions has major influence on the types of patients selected (e.g., broad vs. conservative criteria) and have also highlighted the need for specific subgroups of CFS to be identified and/or for the case definition to be further clarified with emphasis on using empirical studies: An international CFS study group for the CDC found ambiguities in the CDC 1994 CFS research case definition which contribute to inconsistent case identification. Researchers have found that a difference in the self-reported cause of a patient's CFS is associated with significant differences in clinical measures and outcomes, and concluded it is likely that their response to treatment may vary and the CFS definition should be improved to define more homogeneous groups of patients for the purposes of research and treatment. It also might be inappropriate to synthesize results from CFS studies that use different definitions to select study populations. It has been found that identification of new diagnostic symptoms, the use of severity ratings for symptomatology, and the identification of standardized measures that differentiate cases of CFS from other conditions all hold promise for improving the sensitivity, specificity, and reliability of the diagnostic criteria for CFS. Another finding is that the best predictors for people accurately fitting the CDC 1994 definition of CFS are the presence of postexertional malaise, unrefreshing sleep, and impaired memory-concentration, and this accuracy increased when severity of these symptoms were taken into account. Other studies found that the Canadian 2003 definition (a less used but stricter criteria) tends to select cases with less psychiatric co-morbidity, more physical functional impairment, and more fatigue/weakness, neuropsychiatric, and neurological symptoms; while physicians may have a tendency to underrecognize psychiatric illness in people diagnosed with CFS, especially when assessing patients whose chronic fatigue is fully explainable by a psychiatric disorder.
Testing
Although it was originally thought that CFS was related to a viral etiology, more recent studies have failed to find any predictable association between CFS and any particular virus. While there is no test for CFS, a number of exclusionary laboratory tests can be done to rule out other conditions. The CDC recommends the following tests:
* Complete blood count (CBC) - Helps rule out anemia, leukemia and other blood disorders as well as collagen vascular disorders such as lupus.
* Blood chemistry - Confirms normal blood sugar, electrolytes, renal and liver function, calcium and bone metabolism and serum proteins.
* Thyroid function studies - Confirms normal thyroid function, a common cause of muscle aches and fatigue.
* Sedimentation rate - General indicator of inflammation, infection and collagen vascular disorders.
* Urinalysis - Excludes infection, renal disease and possibly collagen vascular disorders.
Diagnostic controversies
Historically, many doctors have been unfamiliar with CFS, and some have refused to diagnose it. This situation is changing somewhat, with more doctors willing to diagnose it. In the UK, the Chief Medical Officer's report stated that all doctors should consider CFS as a serious chronic illness — though it is not stated whether this is a serious physical illness — and treat patients accordingly. Similar progress has been made in the United States. There remains considerable skepticism amongst some medical professionals about the existence of CFS as a 'real' — i.e. medical as opposed to behavioral — condition, possibly due to the extreme uncertainty of its etiology, and the lack of testing for biomedical signs. Many people are inclined to believe that a condition with few or no specific biomedical markers may be psychological in origin. This had led to a frustration in many patients, who feel that their disability is not psychological, but biological. Some patients' groups and experts maintain that research into CFS (ME) in the UK has been mostly hijacked by the psychologists/psychiatric lobby, who they claim hold significant power within the medical fraternity, with a resultant "abuse of patients' rights."[citation needed] The UK and the Netherlands have particularly seen disagreements between biomedical researchers and their adherents, and psychiatrists (particularly proponents of cognitive behavioral therapy, or CBT) and supporters of the theory that CFS is psychological in origin, and can be "cured" entirely by psychotherapy and exercise. A UK Government website allows petitions to be delivered directly to the British Prime Minister. This E-Petition asserts: "We the undersigned petition the Prime Minister to get the Health Service and medical profession to accept the WHO classification of ME/CFS as an organic neurological disorder and not as a psychosocial syndrome." Only British citizens or residents are eligible to sign this E-Petition, which has a deadline of 22nd January 2008. Patients whose illnesses are consistent with the older and Canadian definitions tend most to resent the elevation of what they see as a trivialising, nonspecific sensation of "fatigue" to a principal descriptor. It is thus often important to be able to differentiate between the illness experience of needful patients and an epistemic construct that may or may not select the same target, until a better definition and diagnostic testing is widely accepted.
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Important notice:
The content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other
qualified health provider with any questions you may have regarding a medical condition.
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