Table 2.

Assessment of Motivational Interviewing Treatment Integrity ^a

Measure	Motivational Interviewing (n=38)		Health education (n=37)		Between group standardized mean Difference (95% CI)c	p-value
	Mean ±SD	Aboveb criterion	Mean ±SD	Aboveb criterion
Global ratings (1–5):
Empathy	4.5 ±0.6	95%	2.3 ±1.2	24%	2.3 (1.8 to 2.8)	<0.001
Direction	4.9 ±0.4	97%	4.7 ±0.8	95%	0.3 (−0.2 to 0.8)	0.17
Collaboration	4.2 ±0.9	79%	2.1 ±1.2	14%	2.1 (1.6 to 2.5)	<0.001
Evocation	4.4 ±0.7	92%	2.3 ±1.1	19%	2.2 (1.8 to 2.7)	<0.001
Autonomy support	4.3 ±0.8	87%	2.8 ±1.2	27%	1.5 (1.1 to 2.0)	<0.001
Additional metrics
Giving information (counts)	3.9 ±4.8	n.a	12.8 ±9.5	n.a.	1.2 (0.7 to 1.7)	<0.001
Reflections: Questions (ratio of counts)	3.1 ±2.4	92%	0.2 ±0.3	5%	1.7 (1.2 to 2.1)	<0.001
Open-ended questions (%)	66.0 ±27.6	76%	10.5 ±11.0	3%	2.6 (2.2 to 3.1)	<0.001
Complex reflections (%)	53.9 ±16.3	82%	19.6 ±27.6	24%	1.5 (1.1 to 2.0)	<0.001
MI adherent (%)	79.4 ±37.9	71%	30.3 ±42.6	22%	1.2 (0.8 to 1.7)	<0.001
MI adherent behavior counts	2.3 ±1.7	n.a.	0.8 ±1.3	n.a.	1.0 (0.5 to 1.5)	<0.001
MI non-adherent behavior counts	0.2 ±0.7	n.a.	1.5 ±3.0	n.a.	0.6 (0.1 to 1.1)	<0.001

Note: Boldface indicates significant between group difference, p<0.05.

^aAudio recordings of 75 treatment sessions were randomly selected and scored using the Motivational Interviewing Treatment Integrity Coding¹⁷ by independent expert coders, who were blind to group assignment and study hypotheses.

^bCriteria used: global ratings score ≥4 (1–5 scale); giving information counts - no established criterion; reflection-question ratio = (#reflections / #questions) ≥1.0; % open-ended questions = 100*(#open-ended questions / #total questions) ≥50; %complex reflections=100* (#complex reflections / #total reflections) ≥40%; %MI adherent=100*(# MI adherent behaviors / #MI adherent + #MI non-adherent) = 100%

^cStandardized mean difference, or Cohen’s d, calculated by (mean MI - mean HE) / pooled standard deviation.