ME/CFS Primer/Education Bulletins Response to Sampson’s second letter

Dear Editor,

Sampson’s response takes a “Cartesian” dualistic stance regarding patients with both CFS and a comorbid psychiatric disorder. He assumes such patients have “purely psychiatric disorders” and that they have “psychiatric reasons for their fatigue”. I doubt he would suggest that pain was purely due to “psychiatric reasons” in patients with, for instance, rheumatoid arthritis and depression, so I suggest this interpretation is illogical and unsubstantiated. Incidentally, such patients have as much “bona fide” CFS as those who are not also depressed. To say otherwise is discriminatory. The important thing to remember is to stratify samples by comorbid psychiatric comorbidity when examining psychiatric risk factors for developing CFS, which is exactly what we concluded in our 2001 paper (White et al, 2001).

Sampson goes on to suggest that our 1997 randomised controlled trial of graded exercise therapy (GET) recruited only patients with “psychogenic fatigue”; again being very dualistic (Fulcher & White, 1997). He bases that interpretation on the basis that “30%” of our participants were taking antidepressants (actually it was 45%), and that we excluded those with “appreciable sleep disturbance”.  The facts are that no participant had a mood disorder when recruited (we excluded 74 clinic patients who did have a psychiatric disorder); 59% had not even had a mood disorder during their presented illness; and only three patients were excluded on the basis of “symptomatic insomnia”. At the time of the trial we considered that when a patient complained of significant insomnia, this required treatment in its own right (Myles, 1985). As one would expect in a sample of patients with CFS, their sleep was disturbed when assessed in more detail, with Pittsburgh sleep quality index median (interquartile) scores of 6 (4.5-7.5) and 7 (5.5-8.5) in the two randomised groups. A score of 6 or above is considered abnormal (Buysse et al, 1998). Finally, two thirds of our participants attributed their CFS to a virus.

Sampson finishes his letter by criticising our use of the Oxford criteria for CFS in the PACE trial (White et al, 2007), suggesting this preferentially selects patients “with psychiatric reasons for their fatigue” and that these criteria do not exclude patients with a “primary psychiatric diagnosis in the absence of physical symptoms”. 

This is not the case. One of the reasons we chose the Oxford criteria was because the principal symptom has to be fatigue; something no alternative criteria do. Those where a psychiatric disorder is considered to be explanatory are excluded (Sharpe et al, 1999). Of interest to readers, the PACE trial stratified its sample by both the International criteria for CFS (Reeves et al, 2003) and the London criteria for ME, so we will soon know whether meeting alternative definitions of CFS and ME produces a differential response to non-pharmacological treatments such as GET (White et al, 2007).

Yours faithfully,
Professor Peter White,
Barts and the London School of Medicine, Queen Mary University London, London, UK, EC1A 7BE.   

Buysse DJ, Reynolds CF, Monk TH et al. The Pittsburgh sleep quality index: a new instrument for psychiatric practice and research. Psychiatr Res 1989;28:193-213.

Fulcher KY & White PD. Randomised controlled trial of graded exercise in patients with the chronic fatigue syndrome. British Medical Journal 1997;314:1647-52.

London criteria, quoted in: The National Task Force. Report on Chronic Fatigue Syndrome (CFS), Post Viral Fatigue Syndrome (PVFS) and Myalgic Encephalomyelitis (ME), 1994. Westcare, Bristol.

Myles WS. Sleep deprivation, physical fatigue, and the perception of exercise intensity. Med Sci Sports Exerc 1985;17:580-4.

Reeves WC, Lloyd A, Vernon SD, et al. The international chronic fatigue syndrome study group identification of ambiguities in the 1994 chronic fatigue syndrome research case definition and recommendations for resolution. BMC Health Serv Res 2003, 3. 2.

White PD, Thomas JM, Kangro HO, et al.  Predictions and associations of fatigue syndromes and mood disorders that occur after infectious mononucleosis. Lancet 2001;358:1946-54.

White PD, Sharpe MC, Chalder T, et al; on behalf of the PACE trial group. Protocol for the PACE trial: A randomised controlled trial of adaptive pacing, cognitive behaviour therapy, and graded exercise, as supplements to standardised specialist medical care versus standardised specialist medical care alone for patients with the chronic fatigue syndrome / myalgic encephalomyelitis or encephalopathy. BioMed Central Neurology 2007;7:6