Observational studies have reported inconsistent results for the relationship between chronic smoking and blood pressure and most of the studies are based on the self-reported smoking status. This study was performed to evaluate the relationship of urinary cotinine or self-reported smoking status with blood pressure in Korean adults.Design and Method:
Among individuals enrolled in Kangbuk Samsung Health Study (KSHS) and Kangbuk Samsung Cohort Study (KSCS), 167,868 participants (93,450 men; age 37.5 ± 6.9 years) between 2011 and 2013 who had urinary cotinine measurements were included. Self-reported smoking status was classified as nonsmoker, ex-smoker, and current smoker. Cotinine-verified smoker was defined as urinary cotinine level above 50 ng/mL.Results:
The prevalence of hypertension was 10.0% and 2.8% in men and women, respectively. The prevalence of self-reported smoking was 39.8% in men and 2.4% in women, while the prevalence of cotinine-verified smoking was 37.7% in men and 3.9% in women. The degree of agreement between self-reported and cotinine-verified smoking status in men was higher than in women (k = 0.86 in men and 0.62 in women). Multivariate logistic regression model adjusted for age, body mass index, alcohol drinking, exercise, glucose, total cholesterol, triglyceride, high-density lipoprotein cholesterol, creatinine showed that self-reported current smoking significantly decreased the odds ratio (OR) for hypertension in men compared with nonsmoking (OR [95% CI], 0.80[0.75, 0.86]), but was not in women (1.01 [0.65, 1.56]). These results were similar to those according to cotinine-verified smoking (0.77 [0.73, 0.81] in men and 1.01[0.75, 1.38] in women). Furthermore, log-transformed cotinine level also decreased the OR for hypertension in men (0.92 [0.88, 0.96]), but not women (0.86 [0.68, 1.08]).Conclusions:
This large cohort study shows that the degree of agreement between self-reported and cotinine verified smoking status in women is relatively lower than in men, though urinary cotinine is negatively associated with hypertension in men but not in women.