Table 3.

Psychoactive substance use characteristics at baseline measurement.

Category, substance, and characteristics			App group		Nonapp group		Significancea (app vs nonapp group)	Effect size, r
			VS1b	HS1c	VS2d	HS2e
Legal substances, n (%)
	Alcohol
		Lifetime use	123 (92.5)	94 (88.7)	60 (92.3)	57 (95)	χ21=0.9	.05
		Last month	65 (56)	53 (50.5)	33 (55.9)	40 (67.8)	χ21=2.2	.08
	Tobacco
		Lifetime use	77 (52)	84 (77.6)	42 (59.2)	50 (83.3)	χ21=2.1	.07
		Last month use	35 (45.5)	20 (24.1)	16 (38.1)	12 (24)	χ21=0.4	.04
Illegal substances, n (%)
	Cannabis
		Lifetime use	14 (13.1)	14 (14.1)	10 (17.2)	5 (8.5)	χ21=0.0	.01
		Last month use	2 (1.9)	7 (7.1)	4 (6.9)	1 (1.7)	χ21=0.0	.001
	Ecstasy
		Lifetime use	3 (2.8)	0 (0)	6 (10.3)	1 (1.7)	P=.04f	N/Ag
		Last month use	1 (0.9)	0 (0)	2 (3.4)	0 (0)	P=.56	N/A
	Amphetamines
		Lifetime use	2 (1.9)	1 (1)	3 (5.2)	1 (1.7)	P=.26	N/A
		Last month use	1 (0.9)	0 (0)	2 (3.4)	0 (0)	P=.56	N/A
	Cocaine
		Lifetime use	1 (0.9)	0 (0)	5 (8.6)	1 (1.7)	P=.01h	N/A
		Last month use	1 (0.9)	0 (0)	2 (3.4)	0 (0)	P=.56	N/A
	LSDi/Magic mushroom
		Lifetime use	3 (2.8)	1 (1)	4 (6.9)	0 (0)	P=.47	N/A
		Last month use	2 (1.9)	0 (0)	2 (3.4)	0 (0)	P=.63	N/A
	Heroin
		Lifetime use	1 (0.9)	0 (0)	2 (3.4)	0 (0)	P=.56	N/A
		Last month use	1 (0.9)	0 (0)	2 3.4)	0 (0)	P=.56	N/A
NPSj-type substances, n (%)
	GHBk
		Lifetime use	2 (1.9)	0 (0)	3 (5.2)	0 (0)	P=.36	N/A
		Last month use	1 (0.9)	0 (0)	3 (5.2)	0 (0)	P=.14	N/A
	Mephedrone
		Lifetime use	1 (0.9)	0 (0)	2 (3.4)	0 (0)	P=.56	N/A
		Last month use	1 (0.9)	0 (0)	2 (3.4)	0 (0)	P=.56	N/A
	Pentedrone
		Lifetime use	2 (1.9)	0 (0)	3 (5.3)	0 (0)	P=.36	N/A
		Last month use	1 (0.9)	0 (0)	2 (3.5)	0 (0)	P=.30	N/A
	MDPVl
		Lifetime use	5 (4.7)	0 (0)	3 (5.2)	0 (0)	P=.99	N/A
		Last month use	1 (0.9)	0 (0)	2 (3.4)	0 (0)	P=.56	N/A
	Synthetic cannabinoids
		Lifetime use	6 (5.7)	4 (4.2)	8 (13.8)	3 (5.1)	P=.16	N/A
		Last month use	1 (0.9)	1 (1)	4 (6.9)	0 (0)	P=.19	N/A

^aχ² test or Fisher exact test.

^bVS1: vocational school 1.

^cHS1: high school 1.

^dVS2: vocational school 2.

^eHS2: high school 2.

^fP<.05.

^gN/A: not applicable.

^hP<.01.

ⁱLSD: lysergic acid diethylamide.

^jNPS: novel psychoactive substance.

^kGHB: gamma-hydroxybutyrate.

^lMDPV: methylenedioxypyrovalerone.