A paper published in the online journal Lancet Psychiatry claims that analysis of the PACE trial shows that fear avoidance of exercise plays a strong role in perpetuating fatigue and disability in CFS, and that the best treatment for this is CBT and GET.

This assertion has been challenged by a leading UK expert in ME. Dr Charles Shepherd believes the authors have based their conclusions on a flawed model of illness causation. They have not taken account of the medical complexities involved (muscle, brain and immune system abnormalities), nor of patient experience (exercise programmes make condition worse).

The PACE trial was completed in 2011 at a cost of £5 million and has been widely criticised for the methods used, and the inaccurate way in which it was presented and reported.

Dr Charles Shepherd (Hon Medical Adviser, ME Association):

The ME Association believes that energy management, which involves both physical and mental activity, is the most important aspect of managing ME/CFS.

Consequently, we welcome research which aims to improve our knowledge of how this can best be achieved.

Energy management programmes should be individually tailored. And they must take account of the wide range of clinical presentations and disease pathways that come under the ME/CFS umbrella.

We are therefore very critical of over-simplistic exercise regimes which are based on deconditioning, fear of activity and the assumption that people just need to ‘try harder’ in order to get better.

This approach does not acknowledge the muscle, brain and immune system abnormalities in ME/CFS, which help to provide a physical explanation for the debilitating central (brain) and peripheral (muscle) fatigue that occurs in this illness.

Feedback from patients, who are not normally treated as part of research studies, consistently indicates that around 25% find exercise programmes to be of no value. Around 50% report that their condition worsens as a result.

So the real reason why cognitive behaviour therapy and graded exercise therapy are not producing significant benefits across the whole ME/CFS population is that they are based on a flawed model of illness causation. They are are not taking account of the medical complexities involved.

In our experience, patients with ME/CFS are highly motivated to get better.

They are very willing to take part in energy management programmes that establish a safe baseline of activity, take account of the stage and severity of their illness, involve increases in physical and mental activity that are gradual, flexible and do not result in the person going beyond their limitations and causing symptom exacerbation.

We fear that the results of this study will be interpreted to reinforce the over-simplistic view that rest is bad and exercise is good for people with ME/CFS.

And without discussing the medical complexities involved, they also infer that any reluctance to progressively increase activity levels is far more related to fear or avoidance behaviour than any underlying disease process.

What we desperately need are high quality research studies that are aimed at producing a range of individual energy management programmes based on clinical presentation, stage, and severity of illness.

Read more: ME Association challenges ‘Lancet’ claim about fear of exercise leading to its avoidance in ME/CFS

Research Abstract from Lancet Psychiatry:

Background
Cognitive behaviour therapy (CBT) added to specialist medical care (SMC), or graded exercise therapy (GET) added to SMC, are more effective in reducing fatigue and improving physical function than both adaptive pacing therapy (APT) plus SMC and SMC alone for chronic fatigue syndrome. We investigate putative treatment mechanisms.

Methods
We did a planned secondary mediation analysis of the PACE trial comparing SMC alone or SMC plus APT with SMC plus CBT and SMC plus GET for patients with chronic fatigue syndrome. 641 participants were recruited from six specialist chronic fatigue syndrome clinics in the UK National Health Service between March 18, 2005, and Nov 28, 2008. We assessed mediation using the product of coefficients method with the 12 week measure of the mediators and the 52 week measure of the outcomes. The primary outcomes were fatigue measured by the Chalder fatigue scale and physical function measured by the physical function subscale of the SF-36. We included confounder covariates and used treatment by mediator interaction terms to examine differences in mediator–outcome relations by treatment group.

Findings
The largest mediated effect for both CBT and GET and both primary outcomes was through fear avoidance beliefs with an effect of larger magnitude for GET (standardised effects ×10, CBT vs APT, fatigue −1·22, 95% CI −0·52 to −1·97, physical function 1·54, 0·86 to 2·31; GET vs APT, fatigue −1·86, −0·80 to −2·89, physical function 2·35, 1·35 to 3·39). Increase in exercise tolerance (6 min walk distance) was a potent mediator of the effect of GET (vs APT, fatigue −1·37, 95% CI −0·76 to −2·21, physical function 1·90, 1·10 to 2·91), but not CBT.

Interpretation
Our main finding was that fear avoidance beliefs were the strongest mediator for both CBT and GET. Changes in both beliefs and behaviour mediated the effects of both CBT and GET, but more so for GET. The results support a treatment model in which both beliefs and behaviour play a part in perpetuating fatigue and disability in chronic fatigue syndrome.

Rehabilitative therapies for chronic fatigue syndrome: a secondary mediation analysis of the PACE trial by Prof Trudie Chalder, Kimberley A Goldsmith PhD, Prof Peter D White, Prof Michael Sharpe MD, Prof Andrew R Pickles PhD in The Lancet Psychiatary, Published online 13 January 2015