Mechanisms of motivational interviewing in health promotion: a Bayesian mediation analysis

Abstract

BackgroundCounselor behaviors that mediate the efficacy of motivational interviewing (MI) are not well understood, especially when applied to health behavior promotion. We hypothesized that client change talk mediates the relationship between counselor variables and subsequent client behavior change.MethodsPurposeful sampling identified individuals from a prospective randomized worksite trial using an MI intervention to promote firefighters’ healthy diet and regular exercise that increased dietary intake of fruits and vegetables (n = 21) or did not increase intake of fruits and vegetables (n = 22). MI interactions were coded using the Motivational Interviewing Skill Code (MISC 2.1) to categorize counselor and firefighter verbal utterances. Both Bayesian and frequentist mediation analyses were used to investigate whether client change talk mediated the relationship between counselor skills and behavior change.ResultsCounselors’ global spirit, empathy, and direction and MI-consistent behavioral counts (e.g., reflections, open questions, affirmations, emphasize control) significantly correlated with firefighters’ total client change talk utterances (rs = 0.42, 0.40, 0.30, and 0.61, respectively), which correlated significantly with their fruit and vegetable intake increase (r = 0.33). Both Bayesian and frequentist mediation analyses demonstrated that findings were consistent with hypotheses, such that total client change talk mediated the relationship between counselor’s skills—MI-consistent behaviors [Bayesian mediated effect: αβ = .06 (.03), 95% CI = .02, .12] and MI spirit [Bayesian mediated effect: αβ = .06 (.03), 95% CI = .01, .13]—and increased fruit and vegetable consumption.ConclusionMotivational interviewing is a resource- and time-intensive intervention, and is currently being applied in many arenas. Previous research has identified the importance of counselor behaviors and client change talk in the treatment of substance use disorders. Our results indicate that similar mechanisms may underlie the effects of MI for dietary change. These results inform MI training and application by identifying those processes critical for MI success in health promotion domains.

Evaluating the mechanisms of change in motivational interviewing in the treatment of mental health problems: A review and meta-analysis

“…Current research in the field of substance abuse supports this causal model and also suggests that therapist use of MI-inconsistent behaviours (e.g., confrontation) impede the expression of change talk and relate to worse treatment outcome (Miller & Rose, 2009). While therapist behaviours and patient change talk have been examined in areas such as gambling (Hodgins et al, 2009) and diet and exercise (Pirlott et al, 2012), determining the relevance of these mechanisms in the treatment of varied mental health problems is an avenue for future research that may be fruitful. In order to examine therapist and patient in-session behaviour, consistent use of MI fidelity measures is necessary.…”

“…Given that the focus of MI may differ across populations it is possible that the mechanisms of change in MI for substance use disorders may not apply when MI is used for other disorders. There is some evidence that factors such as change talk and MI consistent behaviours are related to treatment outcome in problem gamblers and patients wishing to improve their diet and physical activity (Hodgins, Ching, & McEwen, 2009;Pirlott, Kisbu-Sakarya, Defrancesco, Elliot, & Mackinnon, 2012), however the relevance of MI change mechanisms to the treatment of psychopathological disorders such as anxiety and eating disorders remains to be examined. Given that MI is related to improved treatment outcomes in these diverse mental health populations , uncovering the mechanisms that contribute to the success of MI treatment may help to tailor MI to specific patient concerns and potentially increase positive therapeutic outcomes.…”

Effectiveness of Total Worker Health interventions.

“…The PHLAME study tested meditational models and assessed the factors involved in the intervention Kuehl, Mabry, Elliot, Kuehl, & Favorite, 2013;Pirlott, Kisbu-Sakarya, Defrancesco, Elliot, & Mackinnon, 2012;Ranby et al, 2011). Process analyses were conducted for the Wellworks-2 (Hunt et al, 2005) and Healthy Directions (Hunt et al, 2007) interventions.…”

Motivational interviewing in obesity reduction

“…Pirlot et al proved the effectiveness of MI in healthy lifestyle promotion (diet modification and chiefly regular exercise) inves-Motivational interviewing in obesity reduction tigating a group of 202 firefighters in the PHLAME program (Promoting Healthy Lifestyles: Alternative Models' Effects) [35]. Similarly, Hillsdon et al and Hardcastle et al demonstrated that MI is successful in interventions aimed at physical activity increase [36,37].…”