Relationship between cigarette smoking and novel risk factors for cardiovascular disease in the United States.

BACKGROUND

Few studies have examined the relationship between cigarette smoking and novel risk factors for cardiovascular disease in a general population or have included a biochemical marker of current smoking.

OBJECTIVE

To examine the relationship between cigarette smoking and serum C-reactive protein, fibrinogen, and homocysteine levels.

DESIGN

Cross-sectional study.

SETTING

The U.S. general population.

PATIENTS

4187 current smokers, 4791 former smokers, and 8375 never-smokers 18 years of age or older who participated in the Third National Health and Nutrition Examination Survey conducted between 1988 and 1994.

MEASUREMENTS

Serum C-reactive protein levels were categorized as detectable (2.2 to 9.9 mg/L) or clinically elevated (> or =10 mg/L), and fibrinogen and homocysteine levels were defined as elevated if in the 85th percentile or greater (11.1 micromol/L and 12.7 mmol/L, respectively).

RESULTS

After adjustment for traditional cardiovascular disease risk factors, cigarette smoking was related to elevated levels of C-reactive protein, fibrinogen, and homocysteine. Compared with never smoking cigarettes, self-reported current cigarette smoking was associated with a C-reactive protein level in the detectable (odds ratio, 1.66 [95% CI, 1.40 to 1.97]; P < 0.001) or clinically elevated (odds ratio, 1.98 [CI, 1.57 to 2.51]; P < 0.001) ranges, with elevated levels of fibrinogen (odds ratio, 2.15 [CI, 1.65 to 2.80]; P < 0.001) and homocysteine (odds ratio, 2.10 [CI, 1.62 to 2.74]; P < 0.001). There were positive and significant dose-response relationships between measures of cigarette smoking (cigarettes per day, pack-years, and serum cotinine levels) and elevated levels of novel risk factors.

CONCLUSIONS

These findings suggest that inflammation and hyperhomocysteinemia may be important mechanisms by which smoking promotes atherosclerotic disease.