Table 4.

Mean Difference (95% CI) in Years of Smoking by Race/Ethnicity Stratified by Age at Smoking Initiation, NHANES 1999–2012

Age at smoking initiation	N	Model 1	Model 2	Model 3	Model 4
Men
Age <16 y
White	583	0.0 (ref)	0.0 (ref)	0.0 (ref)	0.0 (ref)
Black	187	1.0 (−0.8, 2.8)	0.4 (−1.3, 2.2)	0.5 (−1.2, 2.2)	1.0 (−0.7, 2.6)
Mexican American	230	−0.5 (−3.9, 2.9)	−1.6 (−4.9, 1.7)	−1.7 (−5.3, 1.8)	−1.1 (−4.8, 2.6)
Age 16–18 y
White	897	0.0 (ref)	0.0 (ref)	0.0 (ref)	0.0 (ref)
Black	274	3.1 (1.6, 4.7)*	2.1 (0.5, 3.6)*	2.2 (0.7, 3.8)*	2.8 (1.1, 4.4)*
Mexican American	295	−0.3 (−1.9, 1.3)	−2.0 (−3.6, −0.4)*	−1.7 (−3.3, −0.1)*	−0.9 (−2.5, 0.8)
Age >18 y
White	705	0.0 (ref)	0.0 (ref)	0.0 (ref)	0.0 (ref)
Black	195	1.8 (0.3, 3.4)*	1.5 (−0.1, 3.1)	1.9 (0.4, 3.5)*	2.5 (0.9, 4.1)*
Mexican American	281	2.1 (0.3, 4.0)*	1.3 (−0.7, 3.4)	1.4 (−0.6, 3.4)	2.2 (0.2, 4.2)*
Women
Age <16 y
White	412	0.0 (ref)	0.0 (ref)	0.0 (ref)	0.0 (ref)
Black	130	3.5 (1.2, 5.9)*	2.9 (0.4, 5.4)*	2.9 (0.6, 5.2)*	3.2 (0.8, 5.7)*
Mexican American	107	2.3 (-0.5, 5.1)	0.6 (−2.5, 3.8)	0.4 (−2.8, 3.6)	0.8 (−2.6, 4.1)
Age 16–18 y
White	616	0.0 (ref)	0.0 (ref)	0.0 (ref)	0.0 (ref)
Black	195	1.0 (−1.2, 3.1)	0.0 (−2.3, 2.2)	0.1 (−2.2, 2.3)	0.4 (−1.9, 2.7)
Mexican American	154	−0.4 (−2.3, 1.5)	−2.4 (−4.5, −0.3)*	−2.2 (−4.3, -0.1)*	−1.5 (−3.5, 0.5)
Age >18 y
White	494	0.0 (ref)	0.0 (ref)	0.0 (ref)	0.0 (ref)
Black	146	2.8 (1.3, 4.4)*	2.2 (0.6, 3.8)*	2.4 (0.8, 4.1)*	2.4 (0.7, 4.1)*
Mexican American	129	−1.8 (−4.3, 0.6)	−3.1 (−5.7, −0.5)*	−1.8 (−4.2, 0.6)	−1.3 (−3.7, 1.2)

CI = confidence interval; NHANES = National Health and Nutrition Examination Survey. Model 1 adjusted for age, and country of birth. Model 2 further adjusted for education. Model 3 further adjusted for age at smoking initiation. Model 4 further adjusted for intensity of smoking before quitting (number of cigarettes per day at time of quitting). Cutoffs based on tertiles values from weighted distribution.

*p < .05 for t test.