Development and reliability of a Motivational Interviewing Scenarios Tool for Eating Disorders (MIST-ED) using a skills-based intervention among caregivers

•We develop a scenario-based tool for carers in eating disorders called MIST-ED.•This tool is a valid for measuring beginner competence in MI skills.•The MIST-ED shows excellent inter-reliability for both types of responses.•There were no differences between oral and written scenario delivery.•The MIST-ED shows good sensitivity to improve ED skills in caregivers.

The aims of this study were to develop an eating disorder scenarios tool to assess the motivational interviewing (MI) skills of caregivers and evaluate the coding reliability of the instrument, and to test the sensitivity to change through a pre/post/follow-up design. The resulting Motivational Interview Scenarios Tool for Eating Disorders (MIST-ED) was administered to caregivers (n = 66) who were asked to provide oral and written responses before and after a skills-based intervention, and at a 3-month follow-up. Raters achieved excellent inter-rater reliability (intra-class correlations of 91.8% on MI adherent and 86.1% for MI non-adherent statements for written scenarios and 89.2%, and 85.3% for oral scenarios). Following the intervention, MI adherent statements increased (baseline = 9.4%, post = 61.5% and follow-up 47.2%) and non-MI adherent statements decreased (baseline = 90.6%, post = 38.5% and follow-up = 52.8%). This instrument can be used as a simple method to measure the acquisition of MI skills to improve coping and both response methods are adequate. The tool shows good sensitivity to improved skills.