Critical appraisal of evidence base must be understood and respected

EDITOR—The article by Holmes and the accompanying commentaries essentially aim to explore the evidence for the efficacy and effectiveness of the psychotherapies and how this should be applied in everyday clinical practice.1 It is ironic that the arguments against cognitive therapy include numerous instances of idiosyncratic use of research evidence.

Firstly, for example, in his commentary Bolsover selects three studies to support his view that the evidence base for cognitive therapy is weak. We would challenge him to apply his arguments to the seven systematic reviews of cognitive therapy in the Cochrane Database and the Database of Abstracts of Reviews of Effectiveness.2

Holmes and also Bolsover cite a single paper to suggest that cognitive therapy is less effective in the real world of clinical practice than in university based clinical trials. This caricature may have applied to some trials conducted 30 years ago but is irrelevant now. To give just two examples, recent trials of cognitive therapy for chronic depression specifically recruited individuals who were depressed despite adequate trials of pharmacotherapy and psychotherapy.3 Also, the Cochrane review of cognitive therapy for schizophrenia includes examples of “real world” interventions.4

Holmes argues that leading cognitive therapists are starting to question aspects of their discipline. However, these critiques are quoted out of context; the criticisms actually refer to the need to adapt the basic cognitive model to enhance its effectiveness for other disorders. Far from being a weakness, the critical appraisal of cognitive therapy by its practitioners is an important reason why it has been systematically evaluated in such a wide range of conditions.

We agree with Holmes that it is unhelpful to evaluate psychotherapies by using only the research methods applied to drug trials. If clinicians and researchers aspire to an evidence based health service, however, they must …