A re-examination of the evidence base for CBT, using published guidelines for the evaluation of randomised controlled trials [ Guidi et al (2018)], suggests that low intensity interventions and interventions for ME, long term physical conditions and psychosis are not evidence based. Such studies lack credibility either because of the abscence of blind outcome assessment or when blind assessment has been conducted the results have been negative. Further the number of blind credible trials supporting the efficacy of CBT for depression and anxiety disorders is about half the number of studies usually considered as evidence. Dissemination of CBT beyond the boundaries of an evidence base hampers finding real world solutions to a clients difficulties and will likely result in demoralisation of the latter and therapists. This casts doubt not only on the wisdom of IAPT’s expansion beyond depression and the anxiety disorders but the ethics of its’ treatment of staff.
An international team of Experts [Guidi et al (2018) see link below] have developed evaluation guidelines stipulating the need for blind independent assessment of psychological interventions, particularly when psychometric tests are the outcome measure.
The PACE trial for chronic fatigue syndrome was heavily criticised [ Edwards (2017)] because it relied on self-report measures of outcome without blind assessment, a methodology that is unacceptable in medicine and in the evaluation of pharmacological products see https://journals.sagepub.com/doi/full/10.1177/1359105317700886
To my knowledge there are no blinded assessment of outcomes for any low intensity interventions. Efficacy has a way of disappearing when there is blinded assessment, for example Morrison et al (2018) conducted a blinded outcome assessment of CBT for schizophrenia and found no clinically meaningful difference, see link below:
One other stipulation of the Guidi et al (2018) guidelines is that studies of an intervention should involve an active placebo, in order to ensure that any impact of treatment is not just due to raised expectations and attention. But more than 80% of trials in the anxiety disorders have used waiting list control groups [Cuijpers (2016)] as opposed to active placebos .
Carpenter et al’s (2018) , study of anxiety disorders see link below found that there were only 41 studies using an active placebo and in only two thirds of them was there a low risk of bias because outcome assessment was blinded. Thus though CBT was still regarded as efficacious, this number of studies spread across all the anxiety disorders does not make the case for CBT being irrefutable.
As Zhu et al (2014), see link below, put it with regard to generalised anxiety disorder, the evidence for CBT is ‘strong but not definitive’. They point out that although the 12 randomised controlled trials they reviewed all had blind assessors, in 6 of them outcome was not based on the assessors assessment but on a self-report measure.
Of the 144 studies of depression, generalised anxiety disorder, panic disorder and social anxiety disorder reviewed by Cuijpers et al (2016) only half (48.6%) had a blind outcome assessment,
Further Cuijpers et al (2016) found that the effects of CBT are small to moderate when the comparison condition is usual care or active placebo compared to a large effect size when the comparison is a waiting list control condition.
In view of Guidi et al’s (2018) strictures around the evaluation of randomised controlled trials, it is wholly inappropriate for IAPT to admonish its therapists for ‘poor performance’ based solely on a psychometric test. There are surely grounds here for a therapist to claim constructive dismissal.
Dr Mike Scott