Werker et al. [7] claim that several randomised controlled trials have demonstrated that cognitive–behavioural therapy (CBT) resulted in improvement and ‘recovery’ in 60–70 % of adolescent patients with chronic fatigue syndrome when assessed at 6 months [3, 4, 6], with ‘comparable results at 2–3-year follow-up’ [2, 5].

However, I believe further data from the cited research studies would have been helpful to put the results in their full context.

The open-label FITNET trial [4, 5] did indeed report a 63 % ‘recovery’ rate at 6 months. However, the trial used a post hoc definition of ‘recovery’ which has been criticised for not being stringent enough [1, 8]. Furthermore, the follow-up paper concluded that receiving CBT ‘did not significantly influence recovery rates’ at long-term follow-up (LTFU), as there was no significant difference between CBT and the ‘usual care’ control group.

In another cited study, Stulemeijer et al. compared CBT to a waiting list control. The proportion of patients who improved in fatigue and physical function was reported as 60 and 63 %, but when compared to the control group, the additional proportion of patients who improved after CBT was as follows: fatigue severity 39 %; physical functioning 39 %; full school attendance 29 %; and self-rated improvement 27 % [6].

Knoop et al. reported improvement rates of 60–74 %, but when compared to a waiting list control, the improvement rates for CBT at LTFU were 33 % for fatigue, and 24 % for physical functioning, with similar rates at immediate assessment [2].

The remaining cited study, by Lim and Lubitz, investigated an intensive multi­disciplinary inpatient rehabilitation programme. Improvement rates were not presented in comparison to the control group, and 68 % of participants reported that they felt the psychological component of the programme was unhelpful or that they felt indifferent towards it [3].