Appendix II
Letter to the British Medical Journal 312: 1096 27 April 1996
Cognitive behaviour therapy for the chronic fatigue syndrome Patients were not representative of all patients with the syndrome
Editor, - Michael Sharpe and colleagues conclude that cognitive behaviour therapy leads to a sustained reduction in functional impairment for patients with the chronic fatigue syndrome*. The levels of disability of the 60 patients who took part in the study suggest, however, that these patients do not represent a comprehensive cross-section of patients with the syndrome. The 60 patients scored 60-78 on the Karnofsky scale assessing disability and so represent a different population from the 143 patients reported on by Case History Research on ME (myalgic encephalomyelitis), who would have scored 30-60 (R Gibbons et al, first world congress on chronic fatigue syndrome and related disorders, Brussels, Nov 1995). Fifty nine of these 143 reported functional deterioration following sustained, incrementally increased physical exertion.
The authors did not assess other symptoms common in chronic fatigue syndrome, such as pain, nausea, muscle weakness or balance problems - a measure of the reduction of which was taken as a standard for “success” in an earlier trial*. The lack of evidence of significant changes in other measures, besides "the principal complaint of severe fatigue" in the authors’ study tends to diminish the validity of his conclusions.
If functional capacity alone is to be assessed in a trial a validated instrument of measurement should be used. The Karnofsky scale is not sensitive enough to measure function since a value of 80 implies "normal activity with effort; some signs or symptoms of disease". But what does the phrase “normal activity” mean ? Does it mean being able to get up, dress and walk at a level sufficient to maintain (unemployed) independence, or does it mean an ability to perform all these activities together with a return to full-time employment and participation in sport ?
Given the heterogeneous nature of the chronic fatigue syndrome, we are concerned at the apparent enthusiasm for cognitive behaviour therapy, which may be helpful for patients who have factors such as depression or maladaptive behaviour (too much bed-rest) but may in the long term be detrimental to a specific sub-group of patients. We note that in Sharpe and colleagues' trial the condition of four of the 30 patients given cognitive behaviour therapy had deteriorated after 12 months. Could these patients have a distinct type of the chronic fatigue syndrome, meeting the original clinical criteria for myalgic encephalomyelitis*, and be at risk from cognitive behaviour therapy?
RAY GIBBONS, researcher
ANNE MACINTYRE, researcher
CHRIS RICHARDS, researcher
Case History Research on ME (CHROME),
3 Britannia Road,
London SW6 2HJ
* Sharpe M, Hawton K, Simkin S, Surawy C, Hackman A, Klimes I et al. Cognitive behaviour therapy for the chronic fatigue syndrome: a randomised controlled trial. BMJ 1996; 312: 22-6. (6 January)
* Lloyd AR, Hickie I, Brockman A, Hickie C, Wilson A, Dwyer J, et al. Immunologic and psychologic therapy for patients with chronic fatigue syndrome: a double-blind, placebo- controlled trial. AM J Med 1993; 94:197-203
* Ramsay AM. Myalgic Encephalomyelitis and Postviral Fatigue States: the saga of Royal Free disease. Gower Medical Publishing, London, Second Edition 1989; 29-31 32
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