Difference in Carotid Intima-Media Thickness Between Korean and Japanese Men

Purpose: Koreans are recently at higher risk for coronary heart disease than are the Japanese. We aimed to evaluate levels of carotid intima-media thickness (IMT) and coronary risk factors in Korean and Japanese men in the post-World War II birth cohort. Methods: We conducted a population-based study of 352 randomly selected healthy men 40 to 49 years of age: 102 Koreans in Ansan City, Gyeonggi-do, Korea and 250 Japanese in Kusatsu City, Shiga, Japan. Imaging carotid IMT by ultrasonography and other procedures were standardized. Analyzing blood samples and reading carotid IMT were performed at the University of Pittsburgh. Results: Despite more favorable or similar features in coronary risk factors as compared to Japanese men, the Korean men had a higher crude IMT level than the Japanese men (mean ± standard error, 0.655 ± 0.008 mm vs 0.616 ± 0.005 mm, respectively, p < 0.0001). The difference in the levels of carotid IMT significantly remained after adjusting for metabolic and conventional risk factors (0.654 ± 0.008 mm vs. 0.616 ± 0.005 mm, respectively; p < 0.0001). Conclusions: Among men 40 to 49 years of age, Koreans had significantly higher levels of carotid IMT than the Japanese. Factors that underlie the different susceptibility to subclinical atherosclerosis need to be explored.