Evidence-based cognitive-behaviour therapy for eating disorders (CBT-ED) differs from other forms of CBT for psychological disorders, making existing generic CBT measures of therapist competence inadequate for evaluating CBT-ED. This study developed and piloted the reliability of a novel measure of therapist competence in this domain-the Cognitive Behaviour Therapy Scale for Eating Disorders (CBTS-ED). Initially, a team of CBT-ED experts developed a 26-item measure, with general (i.e. present in every session) and specific (context- or case-dependent) items. To determine statistical properties of the measure, nine CBT-ED experts and eight non-experts independently observed six role-played mock CBT-ED therapy sessions, rating the therapists' performance using the CBTS-ED. The inter-item consistency (Cronbach's alpha and McDonald's omega) and inter-rater reliability (ICC) were assessed, as appropriate to the clustering of the items. The CBTS-ED demonstrated good internal consistency and moderate/good inter-rater reliability for the general items, at least comparable to existing generic CBT scales in other domains. An updated version is proposed, where five of the 16 "specific" items are reallocated to the general group. These preliminary results suggest that the CBTS-ED can be used effectively across both expert and non-expert raters, though less experienced raters might benefit from additional training in its use.
Keywords: Eating disorders; cognitive behaviour therapy; competence; reliability; therapist skill.