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

Table 4

Odds ratios (ORs) of behavioral problems according to exposure to tobacco smoke among preschool children.

	Behavioral problems
	(−)	(+)	Crude OR	(95% CI)	Adjusted OR^a	(95% CI)
Number of cigarettes parents currently smoked (cigarettes per day)
0	205	36	1.00	(Ref)	1.00	(Ref)
>0 to 20	123	29	1.34	(0.78–2.30)	1.43	(0.79–2.58)
>20	29	15	2.95	(1.44–6.03)	3.29	(1.48–7.34)
Trend			0.005		0.005
Number of current smokers among cohabiters (persons)
0	200	33	1.00	(Ref)	1.00	(Ref)
1	118	31	1.59	(0.93–2.73)	1.81	(1.00–3.25)
≥2	39	16	2.49	(1.25–4.95)	2.64	(1.20–5.82)
Trend			0.007		0.009
Cumulative exposure to parents’ smoking (range, pack-years)
0	179	26	1.00	(Ref)	1.00	(Ref)
Low (0.07–4.34)	89	25	1.93	(1.06–3.54)	1.76	(0.92–3.40)
High (4.36–14.48)	85	28	2.27	(1.25–4.10)	2.67	(1.38–5.16)
Trend			0.006		0.003
Cumulative exposure to household smoking (range, pack-years)
0	172	26	1.00	(Ref)	1.00	(Ref)
Low (0.05–4.47)	90	26	1.91	(1.05–3.48)	1.76	(0.92–3.39)
High (4.48–24.28)	90	26	1.91	(1.05–3.48)	2.17	(1.10–4.28)
Trend			0.032		0.025
Urinary cotinine levels (range, ng/mg creatinine)
Low (0.03–0.95)	127	19	1.00	(Ref)	1.00	(Ref)
Middle (0.96–2.30)	123	23	1.25	(0.65–2.41)	1.17	(0.59–2.33)
High (2.31–39.7)	107	38	2.37	(1.29–4.36)	2.22	(1.16–4.24)
Trend			0.017		0.041

^aAdjustments 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). CI: confidence interval. Behavioral problem was defined as ≥14 of total difficulty score.