Table 5.

Adjusted estimates, multinomial logistic regression model, for the effect of smoke exposure and the major haplotype pair (CCG/CCG)† of IL13 gene on wheeze phenotypes

Variable	Function‡	estimate	p value	Odds ratio & 95% CI
Boy	1	0.52	0.006	1.69	1.16	2.49
	2	0.64	0.009	1.90	1.18	3.06
	3	0.29	0.275	1.33	0.80	2.23
Birth weight < 2500 g	1	-1.11	0.012	0.33	0.14	0.78
	2	-0.10	0.887	0.91	0.24	3.49
	3	-0.14	0.863	0.87	0.19	4.09
Breast feeding < 3 months	1	-0.03	0.170	0.97	0.93	1.01
	2	-0.06	0.037	0.94	0.88	0.99
	3	0.05	0.116	1.05	0.99	1.11
Having a cat during pregnancy	1	-0.06	0.776	0.94	0.64	1.40
	2	-0.49	0.071	0.62	0.36	1.04
	3	-0.02	0.949	0.98	0.57	1.69
Having a dog during pregnancy	1	0.00	0.980	0.99	0.67	1.49
	2	-0.55	0.050	0.58	0.33	1.00
	3	-0.25	0.401	0.78	0.43	1.40
ETS-2	1	0.52	0.130	1.67	0.86	3.28
	2	0.25	0.573	1.29	0.54	3.08
	3	-0.76	0.245	0.47	0.13	1.68
CCG/CCG	1	-0.06	0.849	0.95	0.54	1.67
	2	-0.57	0.163	0.57	0.25	1.26
	3	0.02	0.945	1.02	0.52	2.01
ETS-2 × CCG/CCG	1	¥ -0.35	0.491	0.66	0.28	1.54
	2	¥1.52	0.014	2.59	1.04	6.44
	3	¥0.70	0.409	2.06	0.45	9.33
ETS-1	1	0.42	0.161	1.52	0.85	2.74
	2	0.40	0.289	1.49	0.71	3.09
	3	0.16	0.687	1.17	0.54	2.52
ETS-1 × CCG/CCG ¥	1	¥ 0.25	0.566	1.21	0.65	2.26
	2	¥ 0.48	0.410	0.92	0.40	2.07
	3	¥ -0.45	0.459	0.65	0.24	1.76

ETS-0, mothers did not smoke during pregnancy and children not exposed to household ETS; ETS-1, mothers did not smoke during pregnancy, but children were exposed to household ETS; ETS-2, mothers smoked during pregnancy and children were exposed to household ETS.

† The most common haplotype pair, inferred from genotype data of five single nucleotide polymorphisms of interleukin 13 gene, rs1800925, rs2066960 and rs20541, using PHASE 2.0.2 software [34].

‡ correspond to a specific wheeze phenotype: Function 1: early-transient (n = 190), 2: early-onset persistent (n = 105), 3: late-onset (n = 70). The reference was the group who never report wheeze up to age 10 (n = 426).

× Denotes an interaction.

¥ For interaction terms, GLIMMIX estimates the Odds Ratio (95% CI) of the combined effect based on the parameter estimate of the main and the interaction effect. For the interaction term, we present the Odds Ratio for two combined effects, but not the statistical significant estimate of the individual interaction term. For example for early-onset persistent wheeze (function 2), the OR for children with the CCG/CCG genotype who had mothers who smoked during pregnancy is exponential (1.5223 + [-0.57]) = 2.59. The OR for maternal smoking during pregnancy (ETS-2 = 1) in children having the CCG/CCG genotype is exponential (-0.2512 + 1.5223) = 5.89 (95% CI: 2.47, 14.1). The difference in the combined effects results from different reference groups (no smoking during pregnancy and not the CCG/CCG genotype, respectively).