Table 1.

Adjusted Marginal Means^a of the Levels of Methylation in Line-1 and Alu Repeated Elements as Well as in the Promoter Regions of Tp53, Cdk2a, Hic1, and Il-6 According to Smoking Status and Number of Cigarettes Smoked Per Day

	N	LINE-1		Alu		TP53		CDKN2A		HIC1		IL-6
		Mean ± SE	p	Mean ± SE	p	Mean ± SE	p	Mean ± SE	p	Mean ± SE	p	Mean ± SE	P
Tobacco smoking status
Nonsmokerb	62	76.0±0.4		24.9±0.2		9.8±0.6		5.9±0.4		16.6±0.9		42.6±1.8
Ex-smoker	7	77.0±1.2	0.388	25.7±0.6	0.174	13.0±2.4	0.151	6.7±1.2	0.536	25.3±3.8	0.012	44.2±5.6	0.786
Smoker	108	75.9±0.3	0.903	25.0±0.1	0.862	10.6±0.5	0.310	6.1±0.3	0.723	19.9±0.8	0.013	39.8±1.2	0.226
Daily cigarette smoking
1–9 cigarettes/day	35	76.0±0.5	0.981	25.0±0.2	0.719	10.0±0.8	0.850	6.0±0.5	0.953	17.6±1.2	0.503	36.4±1.9	0.023
≥ 10 cig/day	73	75.9±0.4	0.904	24.9±0.2	0.974	11.1±0.7	0.170	6.2±0.4	0.656	21.0±1.0	0.002	41.7±1.6	0.719
			0.900c		0.985c		0.149c		0.637c		0.001c		0.961c
Comparison: 1–9 vs ≥ 10 cigarettes/day			0.930		0.713		0.279		0.718		0.029		0.029

Note. ^aEstimated from multiple regression models including as independent variables age, gender, smoking status, tobacco consumption, residence and employment, and percent neutrophils in differential blood counts, as appropriated. The adjusted marginal means of the levels of methyaltion were computed at the average values the other covariates.

^bReference category.

^c p Value for trend between nonsmokers, 1–9 cigarettes/day, and ≥ 10 cigarettes/day.