Association Between Airflow Limitation and Carotid Intima-Media Thickness in the Japanese Population

Purpose: This study aimed to reveal the association between airflow limitation (AL) and carotid intima-media thickness (IMT) according to smoking status in Japan. Subjects and Methods: This cross-sectional study was performed in 2809 subjects, who underwent a comprehensive health examination with pulmonary function tests and carotid ultrasonographic measurement. AL was defined as forced expiratory volume in 1 s/forced vital capacity of < 0.7. The subjects were divided into the following four groups: never smokers without AL, never smokers with AL, former/current smokers without AL, and former/current smokers with AL. Mean IMT, the maximum measurable IMT value in the left and right common carotid arteries (IMT-C max), and mean IMT-C max were measured by carotid ultrasonography. The carotid wall thickness as defined as follows: IMT ≥ 1.1 mm (IMT 1.1 ), IMT-C max ≥ 1.2 mm (IMTc 1.2 ), and IMT-C max > 1.5 mm (IMTc 1.5 ), based on each measured region. The association between AL and the carotid wall thickness according to smoking status was assessed by logistic regression analysis. Results: The mean carotid IMT and mean IMT-C max were significantly higher in never smokers with AL and former/current smokers with or without AL than in never smokers without AL. In logistic regression models adjusted for sex, age, body mass index, hypertension, dyslipidemia, hyperglycemia, physical activity, and alcohol consumption, the risk of carotid wall thickness (IMT 1.1 [odds ratio {OR}: 1.55; 95% confidence interval {CI}: 1.07– 2.24]; IMTc 1.2 [OR: 1.52; 95% CI: 1.03– 2.24]; IMTc 1.5 [OR: 1.99; 95% CI: 1.15– 3.46]) were significantly higher in former/current smokers with AL than in never smokers without AL. Conclusion: The present results suggest that greater IMT and risk of carotid wall thickness were associated with AL and smoking experience.