Update: ME/CFS, GET, The PACE Trial And Fear Avoidance Beliefs

Exercise And ME/CFS: The Controversial Subject Continues – Fear Avoidance Beliefs, A Mediator For The Effect Of CBT And GET?

Please see our page on Exercise And ME/CFS for a background to this story.

Such stories in UK newspapers have appeared in response to the latest publication of a journal article in The Lancet Psychiatry by Prof. White and Prof. Chalder et al. on 13 January 2015:

As this article: “How therapy and exercise ‘may help some with CFS’” on the UK’s NHS website explains: “The UK news headlines covering this complex study have all tended to miss the point slightly. The headlines either focus on the already published results (The Independent), or talk about “fear of exercise” exacerbating CFS (The Daily Telegraph and the Daily Mail) or hindering treatment (The Guardian).

This study did not look at what causes or “exacerbates” CFS, or hinders treatment. It assessed how CBT (Cognitive Behavioural Therapy) and GET (Graded Exercise Therapy) might have improved fatigue and physical function.”

The NHS article’s analysis of the latest PACE Trial retrospective (though pre-planned) analysis of their 2011 data said that the researchers found that the fear avoidance beliefs appeared to be the strongest mediator (factor influencing the outcome) of the effects of both CBT and GET on physical function and fatigue compared with specialist medical care (the “control” treatment). It seemed to account for up to 60% of their effect on these outcomes.

There still remained some weaknesses in the PACE Trial’s data. This was that the main analysis excluded participants with missing data (those subjects who did not complete the study). This has previously been widely criticised as a major flaw in the PACE Trial as a whole – that subjects dropped out part-way through the process – presumably because the treatments were making them worse. The NHS article goes onto say that it is appropriate to eliminate those with missing data if they are missing at random, but if they are particular people – those for whom the treatments were not working very well – this could very well bias the results.

However, the researchers did the analysis including the incomplete data and found it did not differ significantly from the original analysis – so leading them to conclude that the missing data did not have a large effect on the results.

Many patient advocate organisations and charities in the UK have cautioned that the results should not be interpreted as suggesting that ME/CFS is a psychiatric illness. For instance in the article in The Guardian, the chief executive of Action for ME, Sonya Chowdhury is quoted as saying: “This does not mean that ME or CFS is a psychological illness. Nor do we believe that people with ME are afraid of taking part in appropriate activity or exercise – appropriate activity might involve a short walk or, for someone with severe ME, small movements or even sitting up in bed. In this context, fear avoidance is a well-documented factor that can affect the experience of any chronic pain condition, regardless of pathology.”

Likewise, Dr Charles Shepherd, medical adviser for the ME Association, is quoted in the same article as saying: “We fear that the way in which the results of this study will be reported in the media, and in other medical publications, may help to reinforce the view that rest is bad and exercise is good for people with ME/CFS, and that any reluctance to increase activity levels are more related to fear or avoidance behaviour rather than any underlying disease process involving brain and muscle.”

Furthermore, the ME Association has published a statement in response to both the press coverage and the original research article by Prof Chalder et al. It begins with “The claim – made in The Lancet Psychiatry as a follow-up to the PACE Trial published in 2011 – is based on a flawed model of illness causation. It did not take account of the medical complexities involved.”

More recently The British Medical Journal published an article in its Research News section on the afore mentioned Lancet Psychiatry article titled: “Tackling fears about exercise is important for ME treatment, analysis indicates“. This article received a “flood” of  rapid responses. Many of these were critical of the original Lancet Psychiatry article and the methodology of the original PACE Trial. Another responder questions the part of the diverse clinical definitions play in the research and treatments, especially if people with different conditions are being included in studies under the one umbrella term.

However, overall some patients and their advocates (medical doctors and other researchers) believe that if the PACE Trial is accepted as the basis for a “valid treatment” for ME/CFS by policy-makers and practitioners, there will be less impetus for further research into more effective treatments. Moreover, as was evidenced by coverage in UK media in the last weeks, more serious is the fear that the public will think that ME/CFS is less severe, more responsive to treatments and that patients are responsible for their continued condition.


T. Chalder, K. A. Goldsmith, P. D. White, M. Sharpe, A. R. Pickles, “Rehabilitative therapies for chronic fatigue syndrome: a secondary mediation analysis of the PACE trial“, The Lancet Psychiatry, 2015, DOI: http://dx.doi.org/10.1016/S2215-0366(14)00069-8.

White, P. D., 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(9768): 823-836.

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