A high drop-out rate of cognitive behavioural therapy for chronic fatigue

Adamson and colleagues report on 995 patients with chronic fatigue or chronic fatigue syndrome who underwent cognitive behavioural therapy in a naturalistic treatment setting. ¹

The authors report a drop out rate of 31%. This figure refers to patients who did not complete any questionnaires at discharge or follow-up. There is, however, a much higher rate of missing data for each outcome measure separately, reaching 47% for physical functioning and 49% for fatigue and social adjustment at the three-month follow-up. Could the authors clarify why so many patients filled in some but not other outcome measures?

For some outcome measures, the proportion of missing data is not reported. The authors state, for example, that 90% of patients were satisfied with their treatment without clarifying how many patients this figure represents. Could the authors report what percentage of patients failed to provide follow-up data for this outcome measure?

Patients who dropped out seem to be more impaired as they had lower physical functioning, higher Work and Social Adjustment Scale scores, and higher depression scores. At baseline, only 52% of patients met Centers for Disease Control and Prevention criteria for chronic fatigue syndrome. It would be interesting to know if these patients were overrepresented in the dropouts, given that dissatisfaction with cognitive behavioural therapy has frequently been reported in the chronic fatigue syndrome patient community. ²

It is unfortunate that this paper only mentions the positive results of cognitive behavioural therapy for chronic fatigue syndrome. This is not an accurate reflection of the literature as there are large-scale randomised trials that found little evidence for the effectiveness of a cognitive-behavioural approach for chronic fatigue syndrome. ³

Finally, the self-reported global improvement scale used in this study had only six instead of seven options, as is usually the case. Could the authors explain why the option ‘much worse’ was not available in this questionnaire?