Fidelity refers to the extent to which Motivational Interviewing for Opioid Use Disorder (MI-OUD) was implemented as intended. Fidelity can be used to evaluate implementation, and fidelity monitoring is a common component of bundled implementation strategies. Trials of Motivational Interviewing (MI) have generally included fidelity ratings of audio-recorded MI sessions using tools such as the MI Treatment Integrity (MITI) Scale and the MI Skills Code (MISC). These tools are used to measure fidelity as part of training and continuously throughout MI implementation to maintain the spirit of MI delivery over time. A systematic literature review of organizational factors affecting MI implementation noted that a major facilitator of MI fidelity is ample time for training, practicing MI skills, completing fidelity ratings of audio-recorded MI sessions, and self-rating MI delivery for fidelity. Several studies have shown that client change talk associated with high fidelity to MI is also positively associated with improvements in their substance use outcomes.

Adoption is the proportion of eligible health professionals trained to deliver Motivational Interviewing for Opioid Use Disorder (MI-OUD) who actually go on to deliver it. We could not identify any implementation initiatives reporting the adoption of MI-OUD in real-world settings, but did identify studies examining the adoption of Motivational Interviewing for Substance Use Disorder (MI-SUD) across addiction outpatient clinics. Results indicated that adoption was less likely among clinicians who reported lower levels of prior knowledge, acceptance, and experience with the MI-SUD philosophy, as well as those with less peer support and greater caseloads.