Table 6.

Associations of unhealthy behaviors with school and mental difficulties and sustained violence among boys and girls: %.

	Boys (n = 778)				Girls (n = 781)
	Alcohol use	Tobacco use	Cannabis use	Hard drug use	Alcohol use	Tobacco use	Cannabis use	Hard drug use
School and mental difficulties and sustained violence
Grade repetition
Absence	65.2	27.2	8.9	5.3	58.8	24.0	4.6	2.7
Presence	58.1	43.6	20.5	11.1	66.4	51.3	14.2	11.5
Relative risk	0.89	1.60	2.30	2.09	1.13	2.13	3.09	4.26
Chi2 test (P value)	0.141	<0.001	<0.001	0.016	0.130	<0.001	<0.001	<0.001
Depressive symptoms
Absence	63.1	28.5	10.2	5.1	56.0	22.1	4.1	2.2
Presence	76.3	44.1	17.0	18.6	76.5	52.3	14.1	11.4
Relative risk	1.21	1.55	1.66	3.65	1.36	2.37	3.44	5.18
Chi2 test (P value)	0.043	0.012	0.104	<0.001	<0.001	<0.001	<0.001	<0.001
Having sustained violence
Absence	61.9	26.7	9.3	4.6	59.1	26.7	5.1	3.2
Presence	78.6	49.5	19.4	16.5	74.4	48.8	20.9	16.3
Relative risk	1.27	1.85	2.09	3.59	1.26	1.82	4.10	5.09
Chi2 test (P value)	<0.001	<0.001	0.002	<0.001	0.046	0.002	<0.001	<0.001
Being victim of sexual abuse
Absence	63.4	28.4	9.4	4.5	59.0	25.9	4.7	3.1
Presence	90.9	72.7	54.5	63.6	80.0	71.4	34.3	22.9
Relative risk	1.43	2.56	5.80	14.13	1.35	2.76	7.30	7.39
Chi2 test (P value)	0.008	<0.001	<0.001	<0.001	0.013	<0.001	<0.001	<0.001

Bold types: Relative risks higher for girls than for boys.