The route to change: within-session predictors of change plan completion in a motivational interview.

This study is the first to examine within-session therapist and client language/process predictors of a client's decision to complete a written Change Plan in an alcohol-focused motivational interview (MI). Data were from an ongoing hospital-based clinical trial (N = 291). Trained raters coded audiorecorded MI sessions using the Motivational Interviewing Skill Code. Logistic regression analyses found that therapist MI-consistent behaviors (b = .023, p < .001) and client change talk (b = .063, p < .001) were positive predictors, and client counter change talk (b = -.093, p < .001) was a negative predictor of the decision to complete a Change Plan regarding alcohol use. Mean comparisons showed that compared to noncompletion, Change Plan completion did not result in significantly greater changes in client motivational readiness. Completion of a Change Plan is a proximal outcome in MI that is associated with client intention to change (change talk) and may predict follow-up alcohol outcomes. Analyses of such theory-driven proximal client mechanisms provide a more complete model of MI process and may inform MI providers of necessary treatment ingredients.