Cognitive behaviour therapy for adolescents with chronic fatigue syndrome: randomised controlled trial

It is interesting to note that a review of three Dutch CBT studies has just been released[1] which showed that there was no statistically significant increase in physical activity levels in this trial[2].

The review also found there was no statistically significant increase in physical activity levels in the two other Dutch CBT studies investigated [3,4].

The authors of the review (who include Stulemeijer and Bleijenberg) say that, in the three studies, "treatment was based on the manual of CBT for CFS described in detail by Bleijenberg et al. (2003)"[5]. The review analysed fatigue levels, which were also reduced by CBT in the two other CBT studies. They found that "changes in physical activity were not related to changes in fatigue."

Another research team in the US also found similar results with regard to physical activity[6]. In a study investigating an intervention involving Cognitive Behavior Therapy (CBT) which included encouraging patients for going for longer walks, they found that on the SF-36 Physical Functioning (PF) scale, patients improved from a pre-treatment mean (SD) of 49.44 (25.19) to 58.18 (26.48) post-treatment, equivalent to a Cohen's d value of 0.35. On the Fatigue Severity Scale (FSS), the improvement as measured by the cohen's d value was even great (0.78) from an initial pre- treatment mean (SD) of 5.93 (0.93) to a 5.20 (0.95) post-treatment. However on actigraphy there was actually a numerical decrease from a pre- treatment mean (SD) of 224696.90 (158389.64) to 203916.67 (122585.92) post -treatment (cohen's d: -0.13).

So just because patients report lower fatigue and better scores on the SF-36 PF scale, doesn't mean they're doing more, which is what GET and CBT based on GET claim to bring about.

Further reading shows that another study[7], published over a decade ago, showed the problem of using self-report data in CFS patients. The authors' rationale for the study was: "It is not clear whether subjective accounts of physical activity level adequately reflect the actual level of physical activity. Therefore the primary aims of the present study were to assess actual activity level in patients with CFS to validate claims of lower levels of physical activity and to validate the reported relationship between fatigue and activity level that was found on self- report questionnaires. In addition, we evaluated whether physical activity level adequately can be assessed by self-report measures. An Accelerometer was used as a reference for actual level of physical activity.". The authors reported on the correlations on 7 outcome measures in relation to the actometer readings: "none of the self-report questionnaires had strong correlations with the Actometer. Thus, self-report questionnaires are no perfect parallel tests for the Actometer."

The authors of the 1997 study[7] pointed out that "The subjective instruments do not measure actual behaviour. Responses on these instruments appear to be an expression of the patients' views about activity and may be biased by cognitions concerning illness and disability." This was re-iterated in another paper[8]: "In earlier studies of our research group, actual motor activity has been recorded with an ankle-worn motion-sensing device (actometer) in conjunction with self- report measures of physical activity. The data of these studies suggest that self-report measures of activity reflect the patients' view about their physical activity and may have been biased by cognitions concerning illness and disability."

A corollary of the last statement is that reports of improvement in self-report measures in interventions which change "cognitions concerning illness and disability" may not be reliable. "Improvements" in self-report measures may simply show that patients have changed their cognitions with regard to how they view their illness, disability, symptoms, etc rather than actually representing improvements in activity levels and functional capacity.

Thus, I would suggest that actometers should be used whenever possible in CFS trials where one is investigating whether an intervention has brought about increased activity.

It is also interesting to note that in the large Van der Werf (2000) study[8], which involved 277 CFS patients (and 47 healthy controls), the authors divided the patients up "pervasively passive" (representing 24% of the patients), "moderately active" and "pervasively active". They found that "levels of daily experienced fatigue and psychological distress were equal for the three types of activity patterns". So one can't necessarily tell how active a patient is from the fatigue levels they report.

Incidentally they also said "there were no significant group, gender or interaction effects for the number of absolute large or relatively large day-to-day fluctuations (Table 2 and Table 3)." "The day-to-day fluctuation measures were based on somewhat arbitrary criteria (1 S.D. and 33% activity change). However, when we post hoc tested alternative criteria (50% or 66% activity change), again no significant group differences between controls and CFS patients emerged." Part of the rationale of many behavioural interventions in CFS patients is said to be to reduce "boom and bust" (sample reference,[9]). However, it may be the case that the frequency of this activity pattern in CFS has been exaggerated.

References:

[1] Wiborg JF, Knoop H, Stulemeijer M, Prins JB, Bleijenberg G. How does cognitive behaviour therapy reduce fatigue in patients with chronic fatigue syndrome? The role of physical activity. Psychol Med. 2010 Jan 5:1 -7. [Epub ahead of print]

[2] Stulemeijer M, de Jong LW, Fiselier TJ, Hoogveld SW, Bleijenberg G (2005). Cognitive behaviour therapy for adolescents with chronic fatigue syndrome: randomised controlled trial. British Medical Journal 330. Published online : 7 December 2004. doi :10.1136/bmj.38301.587106.63.

[3] Knoop H, van der Meer JW, Bleijenberg G (2008). Guided self- instructions for people with chronic fatigue syndrome: randomised controlled trial. British Journal of Psychiatry 193, 340–341.

[4] Prins JB, Bleijenberg G, Bazelmans E, Elving LD, de Boo TM, Severens JL, van der Wilt GJ, Spinhoven P, van der Meer JW (2001). Cognitive behaviour therapy for chronic fatigue syndrome: a multicentre randomised controlled trial. Lancet 357, 841–847.

[5] Bleijenberg G, Prins JB, Bazelmans E (2003). Cognitive-behavioral therapies. In Handbook of Chronic Fatigue Syndrome (ed. L. A. Jason, P. A. Fennell and R. R. Taylor), pp. 493–526. Wiley: New York.

[6] Friedberg F, Sohl S. Cognitive-behavior therapy in chronic fatigue syndrome: is improvement related to increased physical activity? J Clin Psychol. 2009 Feb 11.

[7] Vercoulen JH, Bazelmans E, Swanink CM, Fennis JF, Galama JM, Jongen PJ, Hommes O, Van der Meer JW, Bleijenberg G. Physical activity in chronic fatigue syndrome: assessment and its role in fatigue. J Psychiatr Res. 1997 Nov-Dec;31(6):661-73.

[8] van der Werf SP, Prins JB, Vercoulen JH, van der Meer JW, Bleijenberg G. Identifying physical activity patterns in chronic fatigue syndrome using actigraphic assessment. J Psychosom Res. 2000 Nov;49(5):373 -9.

[9] Deary V, Chalder T: Chapter 11, "Conceptualisation in Chronic Fatigue Syndrome" in Formulation and Treatment in Clinical Health Psychology Edited by Ana V. Nikcevic, Andrzej R. Kuczmierczyk, Michael Bruch

Competing interests: None declared