A multivariate meta-analysis of motivational interviewing process and outcome

Area of Science:

• Psychology
• Behavioral Science

Background:

• Motivational interviewing (MI) is empirically supported, yet its proposed mechanisms linking therapist behaviors to client outcomes require further investigation.
• Studies evaluating the relationship between MI process variables (e.g., therapist behaviors, client change talk) and clinical outcomes have yielded inconsistent results.

Purpose of the Study:

• To test differential relationships between MI-consistent/inconsistent therapist behaviors, therapist global ratings, client change talk, and clinical outcomes using multivariate meta-analyses.
• To clarify the process-outcome links within motivational interviewing.

Main Methods:

• Conducted multivariate meta-analyses on data from 19 primary studies (N = 2,614).
• Examined relationships between therapist behaviors (MI-consistent, MI-inconsistent, global ratings), client change talk, client sustain talk, and clinical outcomes.

Main Results:

• MI-consistent therapist behaviors correlated with increased client change talk and sustain talk.
• Higher therapist global ratings (empathy, MI spirit) were linked to more MI-consistent behaviors and client change/sustain talk, but not directly to clinical outcomes.
• Client sustain talk predicted worse outcomes, while client change talk showed no significant relationship with outcomes.

Conclusions:

• Findings offer equivocal support for hypothesized MI process-outcome relationships, similar to prior research.
• Therapist behaviors and global ratings influence in-session client language, but direct links to clinical outcomes are complex and require further study.
• Future research should explore MI mechanisms, particularly the differential impact of therapist behaviors and the role of client sustain talk.