[The same points could be made about a lot of the coverage of the recent PACE Trial follow-up paper]
05 November 2015
PACE trial primary outcomes at 2.5 years
In a BMJ article , Ingrid Torjesen claims that a follow-up study of the PACE trial has shown that: "Two treatments for chronic fatigue syndrome [...] continue to offer long term benefits". The headline boasts that: "Tackling fear about exercise produces long term benefit in chronic fatigue syndrome." The two treatments referred to are cognitive behavioural therapy (CBT) and graded exercise therapy (GET).
It is difficult to understand how the editors of BMJ can justify these assertions, considering that the study reported no useful difference in outcomes between treatment arms . The study clearly shows that CBT and GET had no treatment benefit at 2.5 year follow-up, when compared to an intervention resembling usual care.
The PACE trial was a large randomised trial that compared four interventions for chronic fatigue syndrome: CBT; GET; adaptive pacing therapy (APT); and standardised medical care (SMC). Participants in one trial arm received SMC alone, and the other three groups received either CBT, GET or APT in addition to SMC. SMC resembled usual care and typically provided pharmaceutical symptomatic relief when needed, such as pain and sleep medication, and advice to moderate activity levels.
In 2011 the Lancet reported modest differences at 52 weeks between some treatment arms when assessed using the self-rated primary outcomes measures; the Chalder fatigue scale and SF-36 physical function subscale .
Recently the Lancet Psychiatry reported the primary outcomes at 2.5 year follow-up  which showed that the differences between trial arms seen at 52 weeks were not sustained, and that therefore CBT and GET offered no treatment benefit at long-term follow-up.
The BMJ article acknowledges this, in a contradiction to its headline:
"At the end of the follow-up period [...] there was little difference in outcomes among patients in any of the original four treatment groups."
Either CBT and GET "continue to offer long term benefits" over SMC and APT, or there were no useful differences in outcomes between the trial arms. It is not possible for both to be true, and the data in the Lancet Psychiatry follow-up paper clearly support the latter interpretation.
The BMJ article also discusses the issue of SMC and APT group participants receiving CBT or GET after 52 weeks and before the long-term assessment, and how this may have biased the overall outcomes. However, the accompanying commentary in Lancet Psychiatry , clarifies this issue and states that there was no significant difference between patients who received CBT or GET after 52 weeks and those who did not.
The commentary states: “The authors hypothesise that the improvement in the APT and SMC only groups might be attributed to the effects of post-trial CBT or GET, because more people from these groups accessed these therapies during follow-up. However, improvement was observed in these groups irrespective of whether these treatments were received, and thus this hypothesis remains unproven.” 
1. Torjesen I. Tackling fear about exercise produces long term benefit in chronic fatigue syndrome. BMJ 2015;351:h5771.
2. Sharpe M, Goldsmith KA, Johnson AL, Chalder T, Walker J, White PD. Rehabilitative treatments for chronic fatigue syndrome: long-term follow-up from the PACE trial. Lancet Psychiatry 2015.
3. White PD, Goldsmith KA, Johnson AL et al. Comparison of adaptive pacing therapy, cognitive behaviour therapy, graded exercise therapy, and specialist medical care for chronic fatigue syndrome (PACE): a randomised trial. Lancet. 2011; 377:823-36. http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(11)60096-2/abstract
4. Moylanemail S, Eyre HA, Berk M. Chronic fatigue syndrome: what is it and how to treat? Comment. Lancet Psychiatry 2015. http://dx.doi.org/10.1016/S2215-0366(15)00475-7
Competing interests: No competing interests