Table 4. Cox-proportional hazard analysis using age at onset of habitual smoking censored at non-habitual smokers.

	without rs16969968 as a covariate1			with rs16969968 as a covariate1
Marker	N	Hazard ratio (95%CI)	p value2	N	Hazard ratio (95%CI)	p value2
rs11634351	1273	1.23 (1.07–1.43)	0.005	1288	1.23 (1.05–1.44)	0.008
rs17487514	1273	1.14 (0.97–1.34)	0.11	1288	1.13 (0.95–1.35)	0.15
rs1996371	1272	1.24 (1.07–1.43)	0.004	1288	1.23 (1.05–1.44)	0.008
rs11857532	1271	1.14 (0.99–1.32)	0.05	1288	1.14 (0.98–1.32)	0.09
rs922692	1272	1.24 (1.07–1.43)	0.004	1288	1.23 (1.06–1.44)	0.008

¹Analysis was performed within family clusters using additive model. Age at interview in quartiles, gender, pc1, parental smoking and parental drinking were included as covariates.

²Nominal P values are shown uncorrected for multiple testing. The Bonferroni-corrected significance threshold is P = 0.005.