Comment on: Randomised controlled trial of patient education to encourage graded exercise in chronic fatigue syndrome. [BMJ. 2001]
Editor—Powell et al’s controlled trial of graded physical exercise in chronic fatigue syndrome has several shortcomings.1
Firstly, the only tool that was used to assess the level of physical activity was entirely subjective. This was a single item (the third item) of the 11 item standardised SF-36 health survey questionnaire. Use of this single item alone as a valid measure of physical fitness is hardly acceptable in the absence of objective data.
Secondly, in a randomised study one can only compare like with like. In this case, all patients in the intervention arms had a minimum of three telephone contacts during the first three months. Patients in the control group were abandoned to primary care after the randomisation. Why did the investigators not maintain the same number of telephone contacts with the control group? They could have discussed anything but chronic fatigue.
Thirdly, frequent early contacts with patients in the three intervention groups (and not the control group) might have confounded the outcome measures by positively influencing the results. This view is supported by the maximum difference emerging as early as three months among patients who had had the illness for an average of over four years, with little change thereafter. By speaking to the patients Powell et al might have provided them with a coping strategy that the control group could not access. Furthermore, did the authors ask the patients to keep an activity diary to record the intensity (mild/moderate) and duration (minutes/hours a day) of physical exercise so that they could note any difference across the intervention groups?
Because no objective measures of physical activity (for example, exercise endurance) were included before and after the interventions for assessing outcome in this study, the reported beneficial effects of graded physical exercise are based on weak evidence. Moreover, the authors did not use the current diagnostic criteria to select patients with chronic fatigue syndrome. Why are we reading this in the BMJ?
You can read the full comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1120585/
Source: Chaudhuri A. Patient education to encourage graded exercise in chronic fatigue syndrome. Trial has too many shortcomings. BMJ. 2001 Jun 23;322(7301):1545-6. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1120585/ (Full comment)