Second-Hand Tobacco Smoke in Never Smokers Is a Significant Risk Factor for Coronary Artery Calcification

Study Questions:

Among nonsmokers, how strong is the relationship between subclinical atherosclerosis (measured with coronary artery calcification [CAC]) and second-hand tobacco smoke exposure?

Methods:

Data from the Flight Attendant Medical Research Institute International Early Lung Cancer Action Program screening program were used for the present study. Never-smokers, ages 40-80 years, were included in this analysis. All participants completed a questionnaire on second-hand smoke exposure, and had a low-dose nongated computed tomography scan. The questionnaire provided a quantitative score for total second-hand smoke exposure, as well as separately as a child and as an adult at home and at work; four categories of exposure were identified (minimal, low, moderate, and high exposure). CAC was graded using a previously validated ordinal scale score that ranged from 0-12.

Results:

A total of 3,098 participants were included in this analysis. Participants with more than minimal second-hand smoke exposure were older (55 vs. 53 years of age), more frequently women (64.5% vs. 46.2%), and more frequently had diabetes, hypercholesterolemia, and hypertension than those with minimal second-hand smoke exposure. The prevalence of CAC was 24% (n = 754) and was significantly higher in those with more than minimal second-hand smoke exposure compared with those with minimal second-hand smoke exposure (21% vs. 19%, p < 0.0001). For every decade, the prevalence of CAC was significantly higher for those with more than minimal second-hand smoke exposure compared with those with minimal exposure, for both men (p < 0.0001) and women (p < 0.04). The odds ratios for CAC prevalence were 1.54 (95% confidence interval [CI], 1.17-2.20) for low second-hand smoke exposure, 1.60 (95% CI, 1.21-2.10) for moderate exposure, and 1.93 (95% CI, 1.49-2.51) for high exposure, after adjustment for additional risk factors including age, diabetes, elevated cholesterol, hypertension, and renal disease.

Conclusions:

The investigators concluded that the presence and extent of CAC were associated with extent of second hand-smoke exposure even when adjusted for other risk factors for CAC, suggesting that second-hand smoke exposure causes CAC.

Perspective:

These data demonstrate a dose-dependent and -independent association of second-hand smoke exposure with CAC, thus supporting health policy and medical advice for the avoidance of all levels of second-hand tobacco smoke exposure.

Clinical Topics: Dyslipidemia, Prevention, Atherosclerotic Disease (CAD/PAD), Homozygous Familial Hypercholesterolemia, Hypertension, Smoking

Keywords: Coronary Artery Disease, Atherosclerosis, Tobacco Smoke Pollution, Early Detection of Cancer, Calcinosis, Hypercholesterolemia, Tobacco, Kidney Diseases, Smoke, Cardiology, Confidence Intervals, Hypertension, Diabetes Mellitus, Lung Neoplasms


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