King's College London

Research portal

The long-term effectiveness of cognitive behavior therapy for psychosis within a routine psychological therapies service

Research output: Contribution to journalArticlepeer-review

Original languageEnglish
Article number1658
Number of pages11
JournalFrontiers in Psychology
Accepted/In press14 Oct 2015
Published29 Oct 2015


  • PETERS_ET_AL_15_The_long_term_effectiveness_of_cognitive_behavior_therapy_for_psychosis_within_a_routine_psychological_therapies_service_FrontPsychol

    PETERS_ET_AL_15_The_long_term_effectiveness_of_cognitive_behavior_therapy_for_psychosis_within_a_routine_psychological_therapies_service_FrontPsychol.pdf, 1.29 MB, application/pdf

    Uploaded date:04 Nov 2015

    Version:Final published version

    Licence:CC BY

    Copyright © 2015 Peters, Crombie, Agbedjro, Johns, Stahl, Greenwood, Keen, Onwumere, Hunter, Smith and Kuipers. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

King's Authors


Randomised controlled trials (RCTs) have shown the efficacy of CBTp, however, few studies have considered its long-term effectiveness in routine services. This study reports the outcomes of clients seen in a psychological therapies clinic, set up following positive results obtained from an RCT (Peters et al., 2010). The aims were to evaluate the effectiveness of CBTp, using data from the service's routine assessments for consecutive referrals over a 12 years period, and assess whether gains were maintained at a 6+ months' follow-up. Of the 476 consenting referrals, all clients (N = 358) who received ≥5 therapy sessions were offered an assessment at four time points (baseline, pre-, mid-, and end of therapy) on measures assessing current psychosis symptoms, emotional problems, general well-being and life satisfaction. A sub-set (N = 113) was assessed at a median of 12 months after finishing therapy. Following the waiting list (median of 3 months) clients received individualized, formulation-based CBTp for a median number of 19 sessions from 121 therapists with a range of experience receiving regular supervision. Clients showed no meaningful change on any measure while on the waiting list (Cohen's d <= 0.23). In contrast, highly significant improvements following therapy, all of which were significantly greater than changes during the waiting list, were found on all domains assessed (Cohen's d: 0.44-0.75). All gains were maintained at follow-up (Cohen's d: 0.29-0.82), with little change between end of therapy and follow-up (Cohen's d <= 0.18). Drop-out rate from therapy was low (13%). These results demonstrate the positive and potentially enduring impact of psychological therapy on a range of meaningful outcomes for clients with psychosis. The follow-up assessments were conducted on only a sub-set, which may not generalize to the full sample. Nevertheless this study is the largest of its kind in psychosis, and has important implications for the practice of CBTp in clinical services.

Download statistics

No data available

View graph of relations

© 2020 King's College London | Strand | London WC2R 2LS | England | United Kingdom | Tel +44 (0)20 7836 5454