Table 3.

Perceived changes in frequencies of substance use at 6 months of follow-up (from baseline)

		Mean score baselinea	Mean score follow-upa	Deterio-ration	No change	Improved	P valueb
Frequency of preferred substancec (n = 120)	VA (71)	2.7	1.5	4 (5 %)	24 (34 %)	43 (61 %)	<0.001
	CA (49)	2.8	2.2	2 (4 %)	29 (59 %)	18 (37 %)	<0.001
Cannabisd (n = 49)	VA (28)	2.7	1.5	3 (11 %)	8 (28 %)	17 (61 %)	<0.001
	CA (21)	2.6	1.5	2 (9 %)	6 (28 %)	13 (62 %)	0.006
Amphetamined (n = 43)	VA (24)	2.8	1.2	0 (0 %)	6 (25 %)	18 (75 %)	<0.001
	CA (19)	2.5	1.7	2 (10 %)	7 (37 %)	10 (53 %)	0.026

^aThe ordinal ASI scale (frequency of use in the last 6 months) was defined as follows: 0 = never used; 1 = sometimes, but less than 2–3 times a month; 2 = 1–3 days a week; 3 = everyday use)

^b P value from Wilcoxon signed-rank test

^cPreferred substance according to the ASI interview

^dSub-analyses of specific preferred drug if more than 40 patients reported preference for this substance