Australian case definition – American ME and CFS Society

Comment in: Chronic fatigue syndrome and myalgic encephalomyelitis. [BMJ. 1994]

Comment on: Longitudinal study of outcome of chronic fatigue syndrome. [BMJ. 1994]

EDITOR,-I note that several people writing in the BMY are still confusing myalgic encephalomyelitis with the chronic fatigue syndrome. I wish to clarify matters. From a scientist’s point of view, the main problem is not the term chronic fatigue syndrome but the various diagnostic criteria that go with it. For instance, the strict Australian definition adopted by Wilson et al is similar to that for myalgic encephalomyelitis.2 As a result, it is reasonably certain that in this article the two names probably refer to the same disease.

The “Oxford” criteria used in Britain, however, are far broader, covering all patients whose severe, unexplained fatigue has been present for at least half of the time and for at least six months. The only other requirements are that the fatigue must have had a definite onset and that it affects both physical and mental functioning. Unlike with the strict Australian definition, no immunological criteria have to be met.2 Moreover, there do not have to be appreciable fluctuations in symptoms still a major criterion for myalgic encephalomyelitis.

In terms of prevalence, a recent study found that 17 of 686 (2-5%) attenders in general practice fulfilled the Oxford criteria for the chronic fatigue syndrome.3 When a further four patients who did not meet the criterion of a definite onset were also included the estimated prevalence increased to 3%. In contrast, the prevalence of myalgic encephalomyelitis rarely exceeds 1-5 per 1000.4

Most patients who fulfil the Oxford criteria suffer not from myalgic encephalomyelitis but from more common conditions, notably depression, anxiety states, sleep disorders, and fibromyalgia. None of these disorders occur in epidemics …

You can read the rest of this comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2540201/pdf/bmj00440-0053c.pdf

Source: Goudsmit EM. Chronic fatigue syndrome. Distinguish between syndromes… BMJ. 1994 May 14;308(6939):1297-8. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2540201/

Abstract:

BACKGROUND: Our goals were to determine the prevalence of unusual, debilitating fatigue and the frequency with which it was associated with the chronic fatigue syndrome (CFS) or other physical or psychological illness in an outpatient clinic population.

METHODS: We prospectively evaluated a cohort of 1000 consecutive patients in a primary care clinic in an urban, hospital-based general medicine practice. The study protocol included a detailed history, physical examination, and laboratory and psychiatric testing.

RESULTS: Five patients who came because of CFS studies were excluded. Of the remaining 995, 323 reported fatigue, and 271 (27%) complained of at least 6 months of unusual fatigue that interfered with their daily lives. Of the 271, self-report or record review revealed a medical or psychiatric condition that could have explained the fatigue in 186 (69%). Thus, 85 (8.5%) of 995 patients had a debilitating fatigue of at least 6 months’ duration, without apparent cause. Of these patients, 48 refused further evaluation, and 11 were unavailable for follow-up; 26 completed the protocol. Three of the 26 were hypothyroid, and one had a major psychiatric disorder. Of the remaining 22 patients, three met Centers for Disease Control and Prevention criteria for CFS, four met British criteria, and 10 met the Australian case definition. The point prevalences of CFS were thus 0.3% (95% confidence interval [CI], 0% to 0.6%), 0.4% (95% CI, 0% to 0.8%), and 1.0% (95% CI, 0.4% to 1.6%) using the Centers for Disease Control and Prevention, British, and Australian case definitions, respectively. These estimates were conservative, because they assumed that none of the patients who refused evaluation or were unavailable for follow-up would meet criteria for CFS.

CONCLUSIONS: While chronic, debilitating fatigue is common in medical outpatients, CFS is relatively uncommon. Prevalence depends substantially on the case definition used.

Source: Bates DW, Schmitt W, Buchwald D, Ware NC, Lee J, Thoyer E, Kornish RJ, Komaroff AL. Prevalence of fatigue and chronic fatigue syndrome in a primary care practice. Arch Intern Med. 1993 Dec 27;153(24):2759-65. http://www.ncbi.nlm.nih.gov/pubmed/8257251