Development and initial pilot validation of a treatment fidelity instrument for family-based interoceptive exposure for adolescents with low-weight eating disorders

This pilot study outlines the development and psychometric evaluation of a therapist adherence coding measure for a novel treatment, Family-Based Treatment Interoceptive Exposure (FBT-IE). The IE Adherence Coding Framework (IE-ACF) was developed from the FBT-IE Manual using an iterative process. Items on the IE-ACF were coded by two independent coders as either present or absent with therapists considered adherent if both independent coders coded the item as "present." Videotaped sessions of FBT-IE of 30 adolescents with low-weight eating disorders (DSM-5 typical/atypical anorexia nervosa) and their families were coded. Participants received the FBT-IE intervention as part of a randomized controlled trial. Seventy FBT-IE videos were coded. The IE-ACF identified a mean (SD) rating of 80% (±5%) therapist adherence to the protocol across the six-session treatment, with a per item adherence ranging from 36-100%. Two independent coders demonstrated moderate to almost perfect inter-rater reliability (κ range 0.78-0.96) across the sessions. IE-ACF measured therapist adherence to our novel FBT-IE treatment for adolescents with low-weight eating disorders. Through this study, we demonstrated that 1) our therapists were adherent to the FBT-IE manual in the context of an ongoing clinical trial and 2) that independent coders reliably coded sessions using our novel IE-ACF.