Assessment of motivational interviewing: a qualitative study of response process validity, content validity and feasibility of the motivational interviewing target scheme (MITS) in general practice

Riëtta Oberink, Saskia M. Boom, Nynke van Dijk, Mechteld R. M. Visser

The Motivational Interviewing target Scheme (MITS) is an instrument to assess competency in Motivational Interviewing (MI) and can be used to assess MI in long and brief consultations. In this qualitative study we examined two sources of the Unified Model of Validity, the current standard of assessment validation, in the context of General Practice. We collected evidence concerning response process validity and content validity of the MITS in general practice. Furthermore, we investigated its feasibility. Assessing consultations of General Practitioners and GP-trainees (GPs), the assessors systematically noted down their considerations concerning the scoring process and the content of the MITS in a semi-structured questionnaire. Sampling of the GPs was based on maximum variation and data saturation was used as a stopping criterion. An inductive approach was used to analyse the data. In response to scoring problems the score options were adjusted and all consultations were assessed using the original and the adjusted score options. Twenty seven assessments were needed to reach data saturation. In most consultations, the health behaviour was not the reason for encounter but was discussed on top of discussing physical problems. The topic that was most discussed in the consultations was smoking cigarettes. The adjusted score options increased the response process validity; they were more in agreement with theoretical constructs and the observed quality of MI in the consultations. Concerning content validity, we found that the MITS represents the broad spectrum and the current understanding of MI. Furthermore, the MITS proved to be feasible to assess MI in brief consultations in general practice. Based on the collected evidence the MITS seems a promising instrument to measure MI interviewing in brief consultations. The evidence gathered in this study lays the foundation for research into other aspects of validation.