Effect of the G-308A polymorphism of the tumor necrosis factor (TNF)-α gene promoter site on plasma levels of TNF-α and C-reactive protein in smokers: a cross-sectional study

Table 1 Subject characteristics in relation to smoking status

	Smoking status
Variable	Non-smokers for >6 months n = 198	Irregular smokers n = 24	Regular smokers n = 78	P-value^a
Gender [% male]	86	80	88	0.52
Age [years]	42.1 ± 9.0	40.6 ± 9.2	40.0 ± 9.6	0.09
LDL [mg/dl]	122.3 ± 28.5	117.4 ± 30.4	115.9 ± 28.3	0.10
HDL [mg/dl]	45.3 ± 10.8	47.1 ± 8.3	41.4 ± 9.2	0.01
Systolic blood pressure [mmHg]	132.9 ± 15.2	128.7 ± 9.9	131.2 ± 13.6	0.43
Diastolic blood pressure [mmHg]	82.9 ± 9.7	79.2 ± 8.0	81.6 ± 8.3	0.33
Glycosylated hemoglobin [%]	5.15 ± 0.5	5.1 ± 0.4	5.25 ± 0.4	0.12
Tumor necrosis factor-α [ng/l]	1.8 ± 0.5	1.8 ± 1.0	2.2 ± 2.5	0.61
C-reactive protein [mg/l]	1.0 (0.47–1.9)	0.80 (0.5–2.0)	1.75 (0.7–3.0)	0.006

^a P-values for comparisons between non-smokers and regular smokers. Tumor necrosis factor-α and C-reactive protein (CRP) levels were compared using the Wilcoxon test; for all other continuous variables the Student t-test was employed. Values are means ± SD except for CRP where the median and interquartile range is provided. LDL = Low-density lipoprotein cholesterol, HDL = High-density lipoprotein cholesterol

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