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2	A Meta-Analysis of Research on Motivational Interviewing Treatment Effectiveness (MARMITE) Jennifer Hettema Julie Steele William R. Miller Annual Review of Clinical Psychology Vol 1, 2005 (in press)
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4	Adoption Curve for Innovations
5	Number of MI Publications
6	MI Outcome Trials
7	Inclusion Criteria for MI Trials For within-group effect sizes: At least one treatment group including MI At least one post-treatment outcome measure For between-group effect sizes: At least one control or comparison condition without MI components Procedure for creating pre-treatment equivalence of groups
8	All studies double-coded for: Methodological quality on 12 dimensions Other study characteristics Attributes of the MI intervention(s) Within-group effect sizes Between-group effect sizes
9	Effect sizes were computed: For all reported outcome variables At all reported follow-up points For all between-group contrasts With 95% confidence intervals Correcting for small sample bias
10	72 studies included so far: Alcohol (31) One study each: Drug Abuse (14) Gambling Smoking (6) Eating Disorders HIV Risk (5) Relationships Treatment Compliance (5) Water purification (4) Diet and exercise (4)
11	Types of Comparisons MI vs. Specified Treatment (25) MI vs. Treatment as Usual (6) MI vs No Treatment / Placebo (21) MI added to Specified Treatment (7) MI added to Treatment as Usual (5) Mixed Designs (6) Within-Group Only (2)
12	Methodological Quality Compared to 361 alcohol treatment trials: MQS Mean = 10.76 vs. 10.68 (ns) Intervention quality control 78% vs 57% Multisite trials: 28% vs. 5% Follow-up > 12 months 18% vs. 51% Follow-up completion > 70% 45% vs. 75%
13	Outcome (Dependent) Measures Mean of 3.3 outcome variables per study Range: 1 to 12 To avoid capitalization on change, we computed a combined effect size (d) averaging across all reported outcome variables in each study
14	Specified Characteristics of MI Being collaborative Client centered Nonjudgmental Building trust Reducing resistance Increasing readiness Increasing self-efficacy Reflective listening Increasing discrepancy Eliciting change talk Exploring ambivalence Expressing empathy
15	Specified Characteristics of MI Of 12 possible characteristics of MI, The average number mentioned was 3.6 Range: 0-12
16	Treatment “Dose” of MI Average “dose” of 2 sessions (2.2 hours) The contrasts in dose varied from: Comparison group 25 hours longer than MI to MI 6 hours longer than no-treatment
17	Quality Control of MI Average training time: 10 hours (N=13) Manual-guided 74% Post-training supervision 29% Fidelity checks 36%
18	Where was MI tested? Outpatient clinics (15) Inpatient facilities (11) Educational settings (6) Community organizations (5) G.P. offices (5) Prenatal clinics (3) Emergency rooms (2) Halfway house (2) EAP Telephone (3) In home (1) Jail (1) Mixed (7) Unspecified (8)
19	Who delivered MI? Paraprofessionals / students (8) Master’s level (6) Psychologists (6) Nurses (3) Physicians (2) Dietician (1) Mixed (22)
20	Sample Characteristics (N = 14,267) N = 21 to 952 Mean = 198 Males = 54.8% Range = 0 to 100% Mean Age = 34 Range = 16 to 62 Ethnic minorities: 43% (N = 37)
21	Some Generalizations Wide variability in effect size across studies, within problem areas (e.g., for alcohol problems, d varies from 0 to 3.0) Effects of MI appear early Effects of MI diminish over time, except in additive studies d = .77 at post-treatment d = .31 at 4-6 months d = .30 at 6-12 months
22	Effect Size of MI Over Time
23	Effect size was not predicted by: Number of MI attributes mentioned Methodological quality of study, except Use of a manual to guide MI did predict effect size: Studies not using a manual d = .65 Studies using a manual d = .37 Demographic characteristics, except: Anglo/Caucasian samples d = .39 Minority samples d = .79
24	Effect size varied with outcome measures Alcohol: Quantity of drinking d = .30 Frequency of drinking d = .31 BAC estimates d = .22 Negative consequences d = .08 HIV Risk: Knowledge d = 1.46 Behavioral Intentions d = .88 Sexual risk-taking d = .07
25	Mean Combined Effect Size by Problem Area (N=72 Clinical Trials)
26	Conclusions 1. Robust and enduring effects when MI is added at the beginning of treatment MI increases treatment retention MI increases treatment adherence MI increases staff-perceived motivation
27	Conclusions 2. The effects of motivational interviewing emerge relatively quickly (This is also true of other treatments)
28	Conclusions 2a. The effects of motivational interviewing emerge relatively quickly This may not be true for certain problem areas or dependent measures where “sleeper” effects occur (e.g., effects of diet and exercise)
29	Conclusions 3. The between-group effects of motivational interviewing tend to diminish over 12 months This is also true of other treatments Between-group differences diminish in part because control/comparison groups “catch up” over time This may not be true of MI’s additive effects with other treatment
30	Conclusions 4. The effects of MI are highly variable across sites and providers This is also true of other treatments, but may be more true with MI Provider baseline characteristics do not predict effectiveness with MI Treatment process variables do Manuals may not be a good idea
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