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Tackling fears about exercise is important for ME treatment, analysis indicates

BMJ 2015; 350 doi: (Published 14 January 2015) Cite this as: BMJ 2015;350:h227
  1. Ingrid Torjesen
  1. 1London

Reducing worry that exercise or activity will worsen symptoms of chronic fatigue syndrome (myalgic encephalomyelitis or ME) is important for the success of cognitive behavioural therapy or graded exercise therapy in reducing fatigue and improving physical function, concludes a new analysis of data from the PACE trial, reported in the Lancet Psychiatry.1

Earlier results from the PACE (adaptive pacing, graded activity, and cognitive behaviour therapy—a randomised evaluation) trial, published in the Lancet in 2011, showed that in a group of 641 patients cognitive behavioural therapy (CBT) and graded exercise therapy (GET) were of more benefit at 52 weeks to people with chronic fatigue syndrome than adaptive pacing therapy (APT) and usual specialist medical care.2

In GET the patient undertakes a personalised and gradually increasing exercise programme delivered by a physiotherapist, whereas in APT the patient adapts their activity levels to the amount of energy they have.

Trudie Chalder, professor of cognitive behavioural psychotherapy at King’s College London, said that although the original PACE trial results indicated that CBT and GET offered safe and effective treatment options for most patients with chronic fatigue syndrome, the improvements seen were moderate. “By identifying the mechanisms whereby some patients benefit from treatment, we hope that this will allow treatments to be developed, improved, or optimised,” she said.

The researchers used mediation analysis to identify the factors—such as physical fitness (as measured by a walking test) and beliefs about activity—through which CBT and GET achieved their beneficial effects on fatigue and overall physical function. These potential mediating factors were measured at 12 weeks, halfway through the patients’ 24 weeks of treatment, except for the walking test, which was assessed at 24 weeks.

Of the factors they analysed, the researchers found that a reduction in fear that exercise or activity would make the symptoms worse (fear avoidance beliefs) had the largest mediated effect on fatigue and physical function in the case both of CBT and GET (standardised effect ×10 for fatigue, CBT versus APT: −1·22 (95% confidence interval −0·52 to −1·97); GET versus APT: −1·86 (−0·80 to −2·89); for physical function, CBT versus APT: 1·54 (0·86 to 2·31); GET versus APT: 2·35 (1·35 to 3·39)). These factors accounted for 51% of the overall effect on physical function for GET and 37% for CBT, when compared with APT. The respective proportions were 61% and 34% for the same comparisons for the effect on fatigue.

Increase in exercise tolerance (metres walked during a six minute walk) was a potent mediator of the effect of GET, when compared with APT (standardised effect ×10 for fatigue: −1·37 (−0·76 to −2·21); for physical function: 1·90 (1·10 to 2·91)), but not CBT.

Other factors, including avoidance of activity, damage beliefs, and catastrophising, were weaker mediators of the effects on fatigue and physical function.

Chalder said, “Our results suggest that fearful beliefs can be changed by directly challenging such beliefs (as in CBT) or by simple behaviour change with a graded approach to the avoided activity (as in GET). Clinically, the results suggest that therapists delivering CBT could encourage more physical activity such as walking, which might enhance the effect of CBT and could be more acceptable to patients.”

The original 2011 study attracted much criticism over its definitions of secondary outcomes, protocol changes, and generalisability, and the results were disputed. Charles Shepherd, an honorary medical adviser to the ME Association, said that evidence from patients collected by the society indicated that “most people with ME/CFS find CBT to be ineffective (or even harmful); around half consistently report that GET makes them feel worse; and the vast majority report that pacing is the most acceptable and effective form of activity management.”3

Chalder said it was important, because individual experiences of the condition were highly variable, that exercise was personalised to the patient and then introduced gradually. “The most important thing is that right at the very beginning when you do the assessment you find out what the person is able to do and then work from there,” she told a press conference.

“On a day when they feel less symptomatic and very energetic they may do more than they are probably able to do and then of course suffer as a consequence. What we try and do is level out their activities so that [they are] more even and more distributed across the week and the day.”


Cite this as: BMJ 2015;350:h227


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