Table 5

Odds ratios (OR) and confidence intervals (CI) for smoking/non-smoking respondents according to selected predictors by age group

		11 years (n = 608)			13 years (n = 554)			15 years (n = 651)			17 years (n = 150)
		OR	95% CI		p	OR		95% CI	p		OR	95% CI	p	OR	95% CI	p
Liking school	0.74	0.28–1.94	0.543	0.55	0.29–1.05	0.072	1.44	0.93–2.23	0.102	1.25	0.39–4.00	0.706
Brother smokes	1.84	0.91–3.71	0.089	2.01	1.13–3.60	0.018	1.50	0.94–2.37	0.086	1.98	0.76–5.16	0.164
Best friend smokes	3.81	1.92–7.57	0.000	2.95	1.69–5.14	0.000	7.33	4.45–12.09	0.000	4.48	1.50–13.41	0.007
Attitude of best friend	0.74	0.49–5.62	0.134	0.68	0.47–0.97	0.033	0.76	0.56–1.03	0.081	0.42	0.22–0.82	0.011
Attitude of family	1.22	0.79–2.19	0.694	1.21	0.66–2.22	0.532	1.53	0.94–2.48	0.084	1.94	0.74–5.09	0.180
Alcohol use	1.66	0.51–1.27	0.413	2.57	0.99–6.71	0.053	1.68	0.96–2.93	0.069	3.09	0.93–10.26	0.065
Playing truant	1.31	0.79–2.20	0.294	1.72	1.16–2.54	0.006	1.83	1.32–2.54	0.000	1.13	0.54–2.33	0.749
Late at school	0.80	0.51–1.27	0.340	1.44	0.94–2.20	0.094	1.28	0.93–1.76	0.124	2.25	1.03–4.92	0.043
Bullying	1.47	0.96–2.21	0.073	1.22	0.88–1.70	0.227	1.15	0.90–1.46	0.273	0.99	0.62–1.56	0.949
Pressure of school tasks	1.52	0.92–2.62	0.105	1.00	0.62–1.62	0.983	1.03	0.71–1.49	0.888	1.47	0.63–3.45	0.375
Coffee drinking	1.39	0.94–2.07	0.097	1.49	1.06–2.10	0.021	1.55	1.14–2.10	0.005	0.83	0.43–1.60	0.582
Helmet wearing	1.16	0.84–1.61	0.375	1.51	1.14–2.00	0.004	1.16	0.94–1.43	0.155	0.68	0.43–1.06	0.086
Watching videotapes	0.85	0.56–1.27	0.429	1.28	0.95–1.73	0.104	0.87	0.69–1.11	0.266	1.56	0.97–2.52	0.067
Somatic complaints	0.84	0.43–1.61	0.593	1.62	0.92–2.85	0.098	1.47	0.93–2.32	0.095	1.88	0.73–4.85	0.191
Medication use	1.81	0.90–3.64	0.095	1.49	0.84–2.64	0.173	0.90	0.56–1.44	0.665	1.03	0.40–2.62	0.954

“Smoking” is defined as smoking at least once a week.