Table 3.

Odds ratios (OR) and their 95% confidence intervals (CI) of risky sexual behaviours by substance use behaviours among adolescents in bivariate and multivariate analyses

Health behaviour	Ever had sexual intercourse	Condom use	Number of sexual partners*		Ever had sexual intercourse	Condom use	Number of sexual partners*
	Model 1	Model 1	Model 1		Model 2**	Model 2**	Model 2**
	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)
			One	Multiple			One	Multiple
Smoking
No	1.0	1.0	1.0	1.0	1.0		1.0	1.0
Yes	4.1 (2.3-7.2)	1.4 (0.7-2.6)	9.5 (4.6-19.3)	17.7 (8.4-37.3)	3.7 (2.0-6.8)		8.4 (3.7-18.8)	16.5 (7.0-39.0)
Tawa use
No	1.0	1.0	1.0	1.0	1.0		1.0	1.0
Yes	3.7 (2.1-6.7)	1.3 (0.7-2.5)	9.8 (4.7-20.8)	16.6 (7.6-36.3)	2.4 (1.3-4.7)		5.7 (2.5-12.8)	10.4 (4.4-24.6)
Tabocco use
No	1.0	1.0	1.0	1.0	1.0		1.0	1.0
Yes	3.5 (2.2-5.5)	1.3 (0.8-2.3)	8.3 (4.7-14.8)	16.4 (9.0-29.8)	2.8 (1.7-4.7)		6.3 (3.3-11.9)	13.7 (6.9-26.9)
Drunkenness
Less often or never	1.0	1.0	1.0	1.0	1.0		1.0	1.0
Often (once or weak or more often)	2.1 (1.4-3.3)	1.4 (0.8-2.4)	2.1 (1.3-3.3)	4.4 (2.6-7.3)	1.7 (1.1-2.8)		1.7 (1.1-2.8)	3.3 (1.9-5.8)
Marijuana use
No	1.0	1.0	1.0	1.0	1.0		1.0	1.0
Yes	4.8 (2.4-9.7)	1.2 (0.6-2.6)	6.5 (2.6-16.2)	24.4 (10.4-57.2)	3.3 (1.6-7.0)		4.5 (1.7-11.6)	17.1 (6.7-43.3)
Other drug use
No	1.0	1.0	1.0	1.0	1.0		1.0	1.0
Yes	2.2 (1.1-4.6)	1.9 (0.8-4.1)	6.0 (2.4-15.1)	20.5 (8.6-48.7)	1.2 (0.6-2.8)		3.0 (1.1-8.2)	9.1 (3.5-24.0)

*Multinomial logistic regression analysis, reference group is none (no sexual partner).

**Adjusted for age, gender, place of residence, material affluence scale, family structure, school performance and plans after graduation.

Statistical significance level was set at p < 0.05.