Table 3.

Changes in possible mechanisms (proximal outcomes) between baseline, 6 months and 12 months

	SUPPORT		TAU		Difference between Intervention Arms
	Mean change since baseline (sd)	P Value	Mean change since baseline (sd)	P Value	Estimate (95% CI)	P Value	Cohen’s d
Self Determination Scale-Perceived Choice
6 months	0.13 (1.13)	0.63	0.30 (0.84)	0.11	−0.18 (−0.80, 0.45)	0.57	−0.18
12 months	0.41 (1.31)	0.30	0.36 (0.74)	0.04	0.05 (−0.83, 0.93)	0.90	0.05
Treatment Motivation - External Reasons
6 months	0.76 (1.58)	0.05	0.03 (1.23)	0.90	0.73 (−0.16, 1.62)	0.11	0.52
12 months	0.14 (1.60)	0.78	−0.04 (1.90)	0.93	0.17 (−1.21, 1.55)	0.80	0.10
Treatment Motivation - Internal Reasons
6 months	−0.18 (0.76)	0.33	−0.26 (0.68)	0.08	0.09 (−0.37, 0.54)	0.69	0.25
12 months	−0.66 (1.34)	0.11	−0.40 (1.27)	0.17	−0.26 (−1.22, 0.70)	0.59	−0.20
Treatment Motivation - Help Seeking
6 months	0.04 (0.64)	0.81	−0.19 (1.08)	0.42	0.23 (−0.33, 0.78)	0.41	0.12
12 months	−0.27 (1.21)	0.47	−0.06 (1.44)	0.86	−0.21 (−1.26, 0.83)	0.68	−0.16
Treatment Motivation - Confidence
6 months	−0.47 (1.36)	0.15	−0.25 (1.20)	0.35	−0.23 (−1.03, 0.58)	0.58	−0.18
12 months	−0.35 (1.39)	0.43	−0.72 (1.68)	0.07	0.37 (−0.84, 1.59)	0.53	0.24
General Self-Efficacy - Sum
6 months	1.79 (4.94)	0.13	1.50 (4.19)	0.11	0.29 (−2.60, 3.17)	0.84	0.06
12 months	5.00 (6.62)	0.03	1.85 (4.02)	0.05	3.15 (−1.54, 7.84)	0.17	0.62

Self-determination scale perceived choice scores range from 1 to 5, with higher values indicating greater levels of self-determination.

Treatment motivation scores range from 1 to 7, with higher values indicating greater treatment motivation.

General self-efficacy scale scores range from 10 to 40, with higher values indicating greater self-efficacy.