Associations between Exposure to Tobacco Smoke and Behavioral Problems in Preschool Japanese Children

Table 3

Means of SDQ scores^a according to exposure to tobacco smoke among preschool children.

	n	Total difficulty score	Peer problems	Hyperactivity	Conduct problems	Emotional symptoms	Prosocial behavior
Number of cigarettes parents currently smoked (cigarettes per day)
0	238	9.06	1.63	3.41	2.13	1.89	6.21
>0 to 20	151	9.52	1.85	3.52	2.17	1.98	5.85
>20	44	11.20	1.90	3.99	2.65	2.66	5.96
		0.020	0.29	0.25	0.11	0.056	0.24
Trend		0.009	0.14	0.13	0.085	0.039	0.18
Number of current smokers among cohabiters (persons)
0	230	8.93	1.59	3.37	2.11	1.86	6.19
1	148	9.75	1.86	3.63	2.17	2.08	5.71
≥2	55	10.74	2.00	3.77	2.61	2.35	6.49
		0.026	0.091	0.31	0.089	0.23	0.024
Trend		0.007	0.032	0.13	0.066	0.086	0.86
Cumulative exposure to parents’ smoking (range, pack-years)
0	204	8.89	1.58	3.29	2.11	1.91	6.25
Low (0.07–4.34)	112	9.52	1.75	3.62	2.13	2.02	5.85
High (4.36–14.48)	112	10.48	2.01	3.82	2.47	2.17	5.94
		0.017	0.053	0.091	0.11	0.53	0.21
Trend		0.004	0.016	0.031	0.059	0.26	0.18
Cumulative exposure to household smoking (range, pack-years)
0	197	8.92	1.56	3.30	2.12	1.94	6.22
Low (0.05–4.47)	114	9.70	1.76	3.73	2.15	2.06	5.98
High (4.48–24.28)	115	10.17	1.99	3.70	2.42	2.06	5.89
		0.070	0.053	0.14	0.24	0.82	0.37
Trend		0.024	0.015	0.099	0.12	0.60	0.18
Urinary cotinine levels (range, ng/mg creatinine)
Low (0.03–0.95)	145	8.72	1.55	3.16	2.12	1.89	6.32
Middle (0.96–2.30)	144	9.09	1.64	3.37	2.11	1.97	5.86
High (2.31–39.7)	144	10.52	2.02	4.00	2.37	2.13	6.01
		0.002	0.015	0.002	0.27	0.58	0.15
Trend		0.005	0.12	<0.001	0.19	0.61	0.73

^aBy analysis of covariance after adjustments for rater (mother, father), sex, age, body mass index, siblings (none, 1st, and 2nd), birthweight, feeding until 3 months old (breast-, mix-, and bottle-fed), age of mother at delivery, mother’s education (≤12, 13–15, ≥16 y), and mother’s depression (yes, no). SDQ: the Strengths and Difficulties Questionnaire; CI: confidence interval.