Medical Debates

Chronic fatigue syndrome: what's in a name?

Med J Aust 1995; 163: 285-286

Is it a recognisable disease entity with a unique pathophysiology, or a ragbag of non-specific symptoms with many causes?

The spectrum of symptoms now known as "chronic fatigue syndrome" (CFS) was first catalogued in 1869 by Beard, who coined the term neurasthenia [1]. Over the next half century the definition broadened, with multiple subdivisions, so that by the 1930s neurasthenia came to be regarded as the "garbage can of medicine" and the label faded into disuse. Nevertheless, the symptom complex remained.

The expansion of clinical laboratories in the 1940s and 1950s was accompanied by increased interest in the investigation of patients with unexplained chronic debility. However, the pitfalls (selection bias in clinic populations, inappropriate choice of controls, and failure to appreciate the poor diagnostic sensitivity and specificity of laboratory tests when employed outside narrowly defined patient groups) were not widely recognised and false conclusions abounded. Thus, in this period "acidosis", "adrenal exhaustion", "subclinical thyroid disease", "hypoglycaemia" and "chronic brucellosis" became popular diagnoses. In the 1980s "chronic Epstein-Barr virus" [2] and "occult coxsackie" [3] infections were incriminated as causes of chronic fatigue, but both have proved illusory. The latest vogue is "chronic Lyme disease" [4], but chances are that it, too, will end up in the dustbin.

On page 294 of this issue of the Journal, Dunstan et al report the detection of organochlorides in the blood of patients with CFS. This preliminary study appears to have two flaws. Firstly, patients were drawn from an "environmental medicine" practice in New South Wales known for its interest in the effects of low level exposure to toxic chemicals [5], which probably resulted in biased patient selection. This, and an inappropriate choice of controls, make the data difficult to interpret despite their statistical significance. Secondly, the organochloride levels reported are commonly found in healthy individuals and are at least two orders of magnitude below those known to cause clinical or laboratory abnormalities in humans with occupational exposure to toxic chemicals. Confirmation of a link between trace environmental contaminants and CFS would require large-scale epidemiological studies, and stringent criteria would need to be satisifed before such a link could be considered causal [6].

Different diagnostic labels for chronic fatigue syndrome
Practitioner Diagnosis
General Practitioner "Bored housewife" syndrome
Microbiologist Chronic Epstein-Barr virus infection
Atypical Lyme Disease
Immunologist Immune dysfunction syndrome
Respirologist Chronic hyperventilation
Neurologist Myalgic encephalomyelitis
Psychoneurosis
Psychiatrist Somatoform disorder
Atypical depression
Clinical ecologist

Multiple chemical sensitivity syndrome
Allergy to the 20th century

Alternative therapist "Candida" syndrome
Vitamin imbalance
Hypoglycaemia
Journalist Yuppie flu

There is an urgent need for high quality clinical research in this field. The review of current diagnostic criteria by Hickie et al on page 314 of this issue is therefore particularly timely. The central question for researchers is an ontological one: is CFS a recognisable disease entity with a unique pathophysiology, or is it a ragbag of common non-specific symptoms with many causes, mistakenly labelled as a "syndrome"? One of the problems with CFS is its diversity of symptoms and aggravating factors. Naturally enough, patients worry that their abnormal physical sensations are caused by a somatic disease and seek the opinons of various specialists according to where they perceive the problem might lie. Practitioners, on the other hand, tend to apply diagnostic labels according to their own beliefs about the nature of the condition (see Box).

Evidence to date has not supported a primary immunological or infectious aetiology for CFS, and there is a growing view that it is likely to represent a disorder of central nervous system function. The possible mechanisms are hotly debated, particularly when it comes to the role of psychological factors. Hickie et al draw parallels between CFS and "atypical depression", but it is not clear that the latter can be regarded as a valid entity if there are no concomitant mood changes [7].

Another contentious issue highlighted by Hickie et al is the overlap with "somatoform" disorders. However there is a fundamental problem of conflicting definitions here. According to the Diagnostic and statistical manual of mental disorders (DSM-IV), somatoform disorders are characteriserd by a range of non-specific physical symptoms which have no medical explanation [8], while CFS is defined according to a similar range of symptoms which have no psychiatric explanation [9]. "Excessive" use of health care (or "abnormal" illness behaviour), which is said to be a characteristic feature of somatoform disorders, is a subjective criterion that relates more to differences in perception between doctor and patient about what kind of complaints warrant medical attention. It is known from studies of other conditions (e.g. irritable bowel syndrome and asthma) that health care-seeking behaviour is a personality characteristic unrelated to the underlying disorder.

Diagnostic labelling can serve many useful purposes, including conceptual, prognostic, therapeutic and socio-cultural ones. However, it can also serve as a cloak for ignorance, prejudice or misguided beliefs. Adoption of the purely descriptive term "chronic fatigue syndrome" has certainly been a useful step forward as it is free of mechanistic prejudices. However, there remains the difficult question of who should be labelled as having CFS, and under what circumstances. On the one hand, excessive medicalisation can sometimes contribute to disability, and even a relatively non-committal label such as "chronic fatigue syndrome" is not always appropriate. On the other hand, a label such as "somatisation disorder" calls into question the reality of illness and renders ambiguous the individual's status as a "patient". According to Lipowski [10], "it [somatisation] involves both mind and body, and, as a mimicry of 'real' disease, is a state of being that is neither wellness nor 'legitimate' sickness". It should be borne in mind that ambiguity may itself hinder an individual's ability to cope with illness [11].

Whatever the underlying mechanisms, the reality of suffering in patients with chronic fatigue states must be recognised. Diagnostic criteria are useful to a point, but they should be applied with a good dose of clinical judgement.

Robert H. Loblay
Director, Allergy Service, Department of Clinical Immunology, Royal Prince Alfred Hospital, Camperdown, NSW.

References

  1. Beard GM. Neurasthenia or nervous exhaustion. Boston Med Surg J 1869: 3: 217-221.
  2. Jones JF, Ray CG, Minnich LL, et al. Evidence for active Epstein-Barr virus infection in patients with persistent unexplained illness. Elevated anti-early antigen antibodies. Ann Intern Med 1985: 102: 1-7.
  3. Calder BD, Warnock PJ, McCartney RA, Bell EJ. Coxsackie B viruses and the post-viral syndrome: a prospective study in general practice. J Roy Coll Gen Pract 1987: 37: 11-14.
  4. Hudson B, Barry R, Sahfren D, et al. Lyme disease–made in Australia. Today's Life Science 1994: 6: 48-52.
  5. Loblay RH. Unorthodox approaches to allergy. Aust Prescriber 1989: 12: 78-79.
  6. Taubes G. Epidemiology faces its limits. Science 1995: 269: 164-169.
  7. Ray C. Chronic fatigue syndrome and depression: conceptual and methodological ambiguities. Psychol Med 1991: 21: 1-9.
  8. American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 4th ed. Washington DC: APA, 1994.
  9. Fukuda K, Straus SE, Hickie I, et al. The chronic fatigue syndrome: a comprehensible approach to its definition and study. Ann Intern Med 1994: 121: 953-959.
  10. Lipowski ZJ. Somatization: the concept and its clinical application. Am J Psychiatry 1988: 145: 1358-1368.
  11. Shalit B. Structural ambiguity and limits to coping. J Hum Stress 1977: 3: 32-45.

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