The association between self-reported versus nicotine metabolite-confirmed smoking status and coronary artery calcification

OBJECTIVE: There are no data comparing the relationship between coronary artery calcification and self-reported and cotinine-verified smoking. This study was carried out to evaluate the relationship between coronary artery calcium (CAC) and urinary cotinine or self-reported smoking status in Korean adults. PARTICIPANTS AND METHODS: Study participants included 22 797 individuals (19 181 men; mean age±SD 39.2±7.1 years) who were enrolled in the Kangbuk Samsung Health Study and Kangbuk Samsung Cohort Study between 2011 and 2013, and who had urinary cotinine and CAC measurements. Cotinine-verified current smokers were defined as having a urinary cotinine level of above 50 ng/ml. RESULTS: The prevalence of never smokers, former smokers, and current smokers according to the self-reported questionnaires was 44.6, 24.2, and 31.2%, respectively, and that of cotinine-verified current smokers was 30.2%. The prevalence of the presence of CAC in self-reported current smokers was higher than that in self-reported never/former smokers (13.7 vs. 10.2%, P<0.001), and that in cotinine-verified current smokers was higher than that in cotinine-verified never smokers (14.0 vs. 10.2%, P<0.001). A multivariate logistic regression model adjusted for the variables with univariate relationships showed that self-reported former smokers and current smokers had significantly increased odds ratio (OR) for the presence of CAC compared with self-reported never smokers [OR (95% confidence interval): 1.20 (1.03-1.40) in former smokers and 1.29 (1.11-1.50) in current smokers]. Cotinine-verified current smokers also showed a significant association with the presence of CAC [1.23 (1.12-1.35)]. Furthermore, log-transformed cotinine levels increased the OR for the presence of CAC [1.03 (1.01-1.05)]. CONCLUSION: This study is the first large cohort study to show that both self-reported and cotinine-verified smoking is associated independently with the presence of CAC in Korean adults.