Table 2.

Effect of Intervention Delivery Format on Outcomes, Net of Other Intervention and Participant Characteristics

Characteristics	Model 1a		Model 2 (k = 15)		Model 3 (k = 17)		Model 4 (k = 16)		Model 5 (k = 17)		Model 6 (k = 17)
	b	95% CI	b	95% CI	b	95% CI	b	95% CI	b	95% CI	b	95% CI
Format (Group = 1)	−0.49 †	[−1.00, 0.01]	−0.49†	[−1.08, 0.10]	−0.44†	[−0.95, 0.07]	−0.71*	[−1.32, −0.09]	−0.56†	[−1.19, 0.07]	−0.57	[−1.85, 0.71]
Average age (years)	0.05	[−0.19, 0.30]	0.06	[−0.17, 0.28]
Hazardous use (y = 1)	0.36	[−0.18, 0.90]			0.28	[−0.23, 0.79]
Duration (minutes)	−0.00	[−0.01, 0.00]					0.00	[−0.00, 0.01]
Personal feedback (y = 1)	0.22	[−0.36, 0.79]							−0.12	[−0.75, 0.51]
MET modality (y = 1)	0.44 †	[−0.09, 0.97]									−0.08	[−1.38, 1.21]
Constant			−0.33	[−3.83, 3.18]	0.41†	[−0.03, 0.84]	0.48*	[−0.00, 0.97]	0.65*	[0.08, 1.23]	0.65	[−0.69, 2.0]
τ2			0.18		0.14		0.15		0.16		0.16
I2res (%)			72.17		63.66		64.78		65.92		69.46
Adjusted R2			7.61		25.88		28.41		11.83		11.89

Note. k = number of studies. b = unstandardized coefficient from meta-regression model. CI = confidence interval. MET = motivational enhancement therapy.

^aModel 1 shows coefficients from six separate bivariate meta-regression models.

^†p < .10.

^*p < .05.