Table 1.

Treatment effects at 30, 60, and 90 days, using generalized linear mixed models with random intercepts, controlling for baseline values

Variable	Intervention vs. control IRR [95% CI]	p
Primary outcome: Drinks per drinking day (with imputed zerosa)
30 days	0.63 [0.32,1.24]	.18
60 days	0.43 [0.20, 0.90]	.028
90 days	0.34 [0.16, 0.70]	.005
Sensitivity analysis: Drinks per drinking day (omitting zerosa)
30 days	0.78 [0.44, 1.38]	.390
60 days	0.58 [0.31, 1.10]	.096
90 days	0.56 [0.29, 1.06]	.078

Percentage days drankb	Mean difference in percentage drinking days	p
30 days	-18.81 [-42.60, 4.98]	.129
60 days	-19.09 [-43.71, 5.53]	.136
90 days	-34.46 [-58.92, -10.00]	.009

	Mean difference	p
Self-efficacy
30 days	21.75 [7.78, 35.71]	.035
60 days	14.25 [-1.24, 29.74]	.07
90 days	12.21 [-2.72, 27.15]	.110
Overall readiness to change (URICA)
30 days	0.43 [-0.64, 1.50]	.426
60 days	0.42 [-0.73, 1.58]	.469
90 days	0.23 [-0.94, 1.39]	.701
Readiness to change: Recognition (SOCRATES)
30 days	1.73 [-1.01, 4.46]	.214
60 days	-0.85 [-3.73, 2.04]	.560
90 days	-0.96 [-3.81, 1.90]	.506
Readiness to change: Ambivalence (SOCRATES)
30 days	0.52 [-1.34, 2.37]	.582
60 days	-0.43 [-2.39, 1.54]	.665
90 days	-0.26 [-2.20, 1.68]	.791
Readiness to change: Taking steps (SOCRATES)
30 days	2.97 [-0.75, 6.68]	.118
60 days	3.05 [-0.94, 7.04]	.134
90 days	3.82 [-0.08, 7.72]	.057

Notes: IRR = incidence rate ratio; 95% CI = 95% confidence interval; URICA = University of Rhode Island Change Assessment; SOCRATES = Stages of Change Readiness and Treatment Eagerness Scale.

^a Best-fitting model was negative binomial;

^b best-fitting model was a normal distribution (linear regression).