Fidelity of motivational interviewing in an American Indian oral health intervention.

Objectives: Assess fidelity of a motivational interviewing (MI) intervention focused on preventing early childhood caries in a cohort of American Indian mothers with newborns.

Methods: Four interventionists were trained to administer an oral health MI intervention. The MI sessions were audio recorded to enable scoring as part of fidelity studies to assess the interventionist's degree of competence in using MI principles. Evaluation of the interventionists was completed using the Motivational Interviewing Treatment Integrity (MITI) 3.1.1. which assesses global ratings and behaviour counts. Two reviewers evaluated and scored the MI sessions; a random sample of twenty per cent of the total interviews was scored by a trained reviewer and fifty per cent of the randomly selected files scored by an external expert. A total of 225 files were coded by the trained reviewer and 121 files by the external expert.

Results: Mean global scores for all interventionists combined were around 4.0 (expert competence). Scores for reflection to question ratios (around 0.6) were below beginner competence. Scores ranged from beginner to expert competence for open-ended questions (54%-56%), complex reflections (38%-43%) and MI-adherent statements (93%-95%). There was variation in competence for the four interventionists when analysed individually. Inter-rater reliability scores for the two reviewers ranged from fair (0.40-0.59) to good (0.60-0.74). The MI interventionist rated the best in the fidelity assessment had the worst study outcomes compared to other interventionists.

Conclusions: Individual interventionists' scores for the MITI global ratings and behaviour counts reflected variation in competence and ranged from below beginner to expert levels. A higher competence level of the interventionist as assessed by the fidelity study was not related to better study outcomes.