Assessment of motivational interviewing: Psychometric characteristics of the MITS 2.1 in general practice.

Objective: Motivational Interviewing (MI) is increasingly used in healthcare. The Motivational Interviewing Target Scheme 2.1 (MITS) can be used to assess MI in short consultations. This quantitative validation study is a sequel to a qualitative study, which showed that the MITS is suitable for low-stakes assessment. We collected validity evidence to determine whether its suitability for high-stakes assessment in the GP-setting.

Methods: Consultations of GPs and GP-trainees were assessed using the MITS. The internal structure was studied using generalizability theory; intra class correlation (ICC), convergent and divergent validity was determined.

Results: Two coders and seven consultations were found to be necessary for high stakes assessment. We found higher ICCs as coders were more experienced. Convergent validity was found; results for divergent validity were mixed.

Conclusion: The MITS is a suitable instrument for high-stakes MI assessments in GP-setting. The number of consultations and coders that are needed for assessment are comparable to other instruments for assessing communication skills. Practice implications: The MITS can be used to assess conversations for their MI consistency in GP-setting where most consultations are relatively short and are only partially dedicated to behaviour change. As the MITS assesses complex communication skills, experienced coders are needed.