. Author manuscript; available in PMC: 2013 Jul 23.

Published in final edited form as: Behav Genet. 2009 Oct 15;40(1):49–58. doi: 10.1007/s10519-009-9301-0

Table 3.

Distribution of selected smoking variables by genotype in ever smoking cases and ever smoking controls, respectively

Variable	A2A2	A1A1 + A1A2	P-value^a	B2B2	B1B1 + B1B2	P-value^a
Pack years, mean ± SD
Case patients	41.87 ± 30.00	46.83 ± 2.50	0.142	42.48 ± 29.64	46.01 ± 33.88	0.296
Control subjects	25.03 ± 26.44	33.99 ± 29.24	0.006	25.61 ± 26.11	33.66 ± 30.24	0.017
Years smoking cigarettes, mean ± SD
Case patients	31.29 ± 13.74	33.79 ± 14.61	0.086	31.93 ± 13.99	32.78 ± 14.36	0.582
Control subjects	21.50 ± 13.82	25.88 ± 14.17	0.009	22.16 ± 13.81	24.99 ± 14.49	0.097
Cigarettes/day, mean ± SD
Case patients	25.50 ± 13.85	26.28 ± 13.69	0.586	25.43 ± 13.79	26.59 ± 13.78	0.440^b
Control subjects	20.64 ± 15.35	24.51 ± 15.16	0.033	20.66 ± 15.18	24.81 ± 15.45	0.025
Age started smoking, mean ± SD
Case patients	17.59 ± 4.05	17.61 ± 4.11	0.968	17.66 ± 4.32	17.47 ± 3.41	0.639^b
Control subjects	18.18 ± 4.64	16.88 ± 3.60	0.007²	17.94 ± 4.55	17.22 ± 3.81	0.169
Duration of smoking cessation, mean ± SD
Case patients	20.32 ± 12.90	19.61 ± 13.27	0.675	19.83 ± 12.88	20.61 ± 13.38	0.661
Control subjects	26.04 ± 12.96	24.24 ± 12.94	0.283	25.86 ± 12.75	24.44 ± 13.40	0.406

P-value is for Student’s t-test

Student’s t-test with unequal variances was used