The extent of exposure to secondhand tobacco smoke is independently associated with the extent of coronary artery calcification (CAC) among never smokers, even after adjusting for other CAC risk factors, according to a study published in JACC: Cardiovascular Imaging.

The study looked at 3,098 never smokers 40 to 80 years of age enrolled in the Flight Attendant Medical Research Institute International Early Lung Cancer Action Program screening program. Participants completed a questionnaire regarding exposure to secondhand smoke and underwent low-dose nongated computed tomography (CT). The overall prevalence of CAC was 24 percent and it was significantly higher among those with more than minimal exposure to secondhand smoke as compared to those with minimal exposure (26.4 percent vs. 18.5 percent, p<0.0001). The odds ratio — adjusted for age, gender, diabetes, hypercholesterolemia, hypertension and renal disease — for CAC prevalence was 1.54 (95 percent confidence interval [CI]: 1.17 to 2.20) for low exposure, 1.60 (95 percent CI: 1.21 to 2.10) for moderate exposure, and 1.93 (95 percent CI: 1.49 to 2.51) for high exposure. The association between the extent of secondhand smoke exposure and extent of CAC was statistically significant (p<0.0001).

Results also showed that when considering exposure to secondhand smoke "in childhood, as an adult at home and as an adult at work separately, each was an independent predictor of the prevalence of CAC. Moreover, it establishes that with increasing secondhand tobacco smoke exposure (SHTS), there is an increase in the extent of CAC and that a significant dose relationship existed," wrote the investigators.

Overall, the study investigators note their findings suggest a causal relationship between SHTS exposure and CAC and urge official recognition of SHTS exposure as an independent risk factor for coronary artery disease. They also suggest inclusion of CAC assessment while screening for lung cancer, as well as continued improvement and availability of low-dose radiation CT scans.

Keywords: Odds Ratio, Coronary Artery Disease, Tobacco Smoke Pollution, Tomography, X-Ray Computed, Risk Factors, Hypercholesterolemia, Prevalence, Surveys and Questionnaires, Confidence Intervals, Workplace, Diabetes Mellitus, Lung Neoplasms, Hypertension