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Moderators of cognitive behavioural therapy treatment effects and predictors of outcome in the CODES randomised controlled trial for adults with dissociative seizures

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Laura Goldstein, Emily J. Robinson, Trudie Chalder, Jon Stone, Markus Reuber, Nick Medford, Alan Carson, Michele Moore, Sabine Landau

Original languageEnglish
Article number110921
JournalJournal of Psychosomatic Research
Issue number110921
PublishedJul 2022

Bibliographical note

Funding Information: This paper describes independent research funded by the National Institute for Health and Care Research (Health Technology Assessment programme, 12/26/01, COgnitive behavioural therapy v. standardised medical care for adults with Dissociative non-Epileptic Seizures: A multicentre randomised controlled trial (CODES)). LHG, TC and SL receive salary support from the National Institute for Health and Care Research (NIHR) Maudsley Biomedical Research Centre at the South London and Maudsley NHS Foundation Trust and King's College London . EJR received salary support from the NIHR Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London . JS is supported by an NHS Scotland NHS Research Scotland (NRS) Career Fellowship and JS and AC also acknowledge the financial support of NRS through the Edinburgh Clinical Research Facility. MR benefitted from the support of the NIHR Sheffield Biomedical Research Centre (Translational Neuroscience). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. Publisher Copyright: © 2022 The Authors

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Objective: We explored moderators of cognitive behavioural therapy (CBT) treatment effects and predictors of outcome at 12-month follow-up in the CODES Trial (N = 368) comparing CBT plus standardised medical care (SMC) vs SMC-alone for dissociative seizures (DS). Methods: We undertook moderator analyses of baseline characteristics to determine who had benefited from being offered CBT 12 months post-randomisation. Outcomes included: monthly DS frequency, psychosocial functioning (Work and Social Adjustment Scale - WSAS), and health-related quality of life (Mental Component Summary (MCS) and Physical Component Summary (PCS) SF-12v2 scores). When moderating effects were absent, we tested whether baseline variables predicted change irrespective of treatment allocation. Results: Moderator analyses revealed greater benefits (p < 0.05) of CBT on DS frequency for participants with more (≥22) symptoms (Modified PHQ-15) or ≥ 1 current (M.I.N.I.-confirmed) comorbid psychiatric diagnosis at baseline. The effect of CBT on PCS scores was moderated by gender; women did better than men in the CBT + SMC group. Predictors of improved outcome included: not receiving disability benefits, lower anxiety and/or depression scores (PCS, MCS, WSAS); shorter duration, younger age at DS onset, employment, fewer symptoms and higher educational qualification (PCS, WSAS); stronger belief in the diagnosis and in CBT as a “logical” treatment (MCS). Some variables that clinically might be expected to moderate/predict outcome (e.g., maladaptive personality traits, confidence in treatment) were not shown to be relevant. Conclusion: Patient complexity interacted with treatment. CBT was more likely to reduce DS frequency in those with greater comorbidity. Other patient characteristics predicted outcome regardless of the received intervention.

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