An international team of Experts led by Jenni Guidi et al (2018) (see dropbox link) has recommended that for all trials of psychological interventions ‘Assessments should be performed blind before and after treatment and at long-term follow up’. But IAPT have been it seems “totally blind” to this need for independent standardised assessment. In the US, without at least alleged independent reliable assessment drug companies would not be allowed to market their wares. However it is apparently OK in the UK to market psychological interventions without any reliable determination of the proportion of people who are ‘well’ (no longer meeting recognised diagnostic criteria for at least 8 weeks, as assessed by a blind independent assessor).
But IAPT is not the only culprit, many of the randomised controlled trials compared CBT to waiting lists, as opposed to attention control groups and probably no more than half used independent blind assessors to assess outcome. This makes the evidence base for CBT more questionable than NICE would suggest. Additionally many of the evaluations of medication do not involve a long term follow up.
Dr Mike Scott