Second-Hand Tobacco Smoke in Never Smokers Is a Significant Risk Factor for Coronary Artery Calcification
Among nonsmokers, how strong is the relationship between subclinical atherosclerosis (measured with coronary artery calcification [CAC]) and second-hand tobacco smoke exposure?
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.
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.
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.
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.
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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