this is the primary outcome measure used in a just published study of CBT for persecutory delusions https://babcpmail.com/AQ0-7G5L5-2KPHRR-4HXKEC-1/c.aspx. But would the typical person suffering from schizophrenia recognise this metric? What if convictions take a variable course and are mood dependent? What is going on here? Unrestrained by such questions Freeman et al (2021) proclaim in their advertisement for the 5 day online course for the Programme:
‘it is the most effective psychological treatment for persecutory delusions. Half of patients have recovery in their persecutory delusion with the Feeling Safe Programme’
‘Recovery’ here has a meaning far removed from common parlance. ‘When I use a word,’ Humpty Dumpty said, in rather a scornful tone, ‘it means just what I choose it to mean – neither more nor less.’ —LEWIS CARROLL, Through the Looking-Glass, 1871. If my conviction about the likelihood of being flooded fell to less than 50%, I would still be wanting to relocate!
Freeman et al (2021) are evaluating their own Feeling Safe Programme but no mention that therefore their study might be prone to allegiance bias. The same therapists administered the Feeling Safe Programme and the comparison Befriending Programme. Given that the therapists knew that the hypothesis was that the former would prove superior to the latter, they are likely to be more enthusiastic about the CBT. Twenty sessions were to be delivered in 6 months in each modality but in the event more sessions were delivered in the CBT. Thus the possibility of allegiance bias amongst the therapists cannot be ruled out. It is therefore not surprising that a statistically significant difference was found between the two arms of the study. But this does not necessarily demonstrate the added benefit of CBT – a further confounding factor is that 71% of those in befriending were on antidepressants compared to 50% in CBT.
Freeman et al (2021) make the common cry of all researchers for more research, but there is no mention of the need for independent replication. This latter is particularly important as previous studies have not demonstrated the added value of CBT for persecutory delusions.
Inappropriate Outcome Measure
Clients in CBT were encouraged to take a 6 session module ( the Feeling Safe Module) targetting threat beliefs, how can the latter then be a credible outcome measure? Broader measures such as functioning as I was before I became paranoid or even as I was when I was least paranoid would have been more credible primary outcome measures. Further the secondary outcome measures used were all based on self-report measures, there was no standardised diagnostic interview conducted. Whilst diagnostic labels were affixed at entry into the study ( on what basis is not clear), they were ignored with regards to outcome.
Is The Effect Size Found Meaningful?
The effect size for the primary outcome measure was a Cohen’s d of 0.86, Freeman et al (2021). The effect size for total delusions score on PSYRATS was d=1.2 Freeman et al (2021) celebrate this large effect size as comparable to that found in trials of CBT for anxiety disorders. But in terms of the primary outcome measure the average person undergoing CBT improved by less than one standard deviation compared to the average person who was befriended, this is shown diagrammatically below, does this amount to a real world difference? The economic analysis promised in the pre-trial protocol was not included in the paper, leaving it an open-question as to whether the CBT is worth the added investment.
Eminence-based Rather Than Evidence-based
Advocates of the Feeling Safe Programme, are claiming more than is known, doubtless BABCP and IAPT will seize on it and control how CBT is to be conducted with this population, extending their empire. Well the study was published in Lancet Psychiatry after all? The CBT therapist should be sceptical, but regrettably training courses seem not to equip them for this, I wonder why? Perhaps I am paranoid?
Dr Mike Scott