A valedictory dispatch from the Psychosocial School?
Does Pragmatic Rehabilitation (PR) reduce the "fatigue" experienced by people diagnosed with CFS/ME according to the Oxford criteria (1)? Wearden et al report in the Abstract of their paper that after 20 weeks of PR participants had "significantly improved fatigue" and, in their linked editorial, Moss-Morris and Hamilton state that participants receiving PR were "significantly less fatigued". However, in the body of the text, Wearden et al describe the improvement as being "small" and "clinically modest". Thus, in the same journal, we find that the effect of PR on fatigue is simultaneously "significant" and "small".
The effect cannot be both large and small, so which interpretation best matches the data?
A participant's fatigue was measured using the 11 item Chalder Fatigue Scale (ChFS) "scored dichotomously on a four point scale (0, 0, 1, or 1)". The ChFS has been criticised because it "has a low ceiling, so patients with maximal scores at baseline will not be able to record an exacerbation after treatment." (2) The maximum one can score on the ChFS is 11, after which it cannot detect further deterioration. It can be seen from the published data that participants receiving PR had a mean baseline ChFS score of 10.49 from which it can be calculated that between 47 and 88 of the 95 participants started therapy with a ChFS score of 11. Therefore, at least half of the participants could not report that PR had worsened their fatigue, even if such were the case. PR involves graded exercise so one would expect this therapy more than "supportive listening" or normal GP treatment (unspecified) to exacerbate fatigue but, had this occurred, the ChFS could not have detected it. Thus, the inability of the ChFS to measure deterioration in this patient cohort biases the trial in favour of finding "improvements" in fatigue and, in particular, favours PR because exercise-induced relapses cannot be recorded.
A genuine improvement in fatigue would, axiomatically, lead to increased physical capacity, but no statistically significant change in physical function was found in the PR group and, in fact, participants randomised to the control group (GP treatment as usual) experienced greater improvement in physical function.
Thus the conclusion that PR led to a real improvement in participants' fatigue must be interpreted with caution.
The authors suggest that "treatment effects may have been enhanced had we been able to provide post-treatment booster sessions." However, it is instructive to note that the mean ChFS score fell from 10.49 at baseline to 8.39 after 20 weeks of therapy where, according to the text, "total scores of four or more on the fatigue scale designate clinically significant levels of fatigue." Therefore, even if extra sessions had trebled the efficacy of Pragmatic Rehabilitation, participants would still have "clinically significant levels of fatigue".
Notwithstanding, Wearden et al comment: "it is likely that our trial gives an accurate indication of the effectiveness of nurse delivered pragmatic rehabilitation and supportive listening for CFS/ME in primary care." Indeed it does: the data provide strong evidence that the anxiety and deconditioning model of CFS/ME on which the trial is predicated is either wrong or, at best, incomplete. These results are immensely important because they demonstrate that if a cure for CFS/ME is to be found, one must look beyond the psycho-behavioural paradigm.
(1) Sharpe MC, Archard LC, Banatvala JE, et al. (February 1991). "A report--chronic fatigue syndrome: guidelines for research". J R Soc Med 84 (2): 118–21
Competing interests: No competing interests