Assessing fidelity to integrated motivational interviewing and CBT therapy for psychosis and substance use: the MI-CBT fidelity scale (MI-CTS)

Abstract

Background Guidelines for the psychological treatment of psychosis and substance use suggest integrated treatments to address both problems are necessary. One such treatment combines cognitive-behaviour therapy (CBT) and motivational interviewing (MI). While there are a number of scales to assess treatment fidelity to CBT and MI separately, none, to date, assess fidelity to integrated MI and CBT (MI-CBT) for psychosis and substance use. Aims This study aimed to develop a reliable and valid scale to assess fidelity to MI-CBT for people with psychosis and problematic substance use. Method Items for a new scale (the MI-CTS fidelity scale) were selected from multiple relevant sources. Inter-rater reliability and validity (against the CTS-Psy and Motivational Interviewing Treatment Integrity (MITI)) scales were investigated. Results The scale had good inter-rater reliability when used to rate adherence versus non-adherence. In relation to validity, the scale related well to CBT and MI scales (the CTS-Psy and MITI). Conclusions The MI-CTS is useful for assessing adherence to integrated MI-CBT for psychosis and substance misuse and could aid training and implementation of the approach.