Plasma homocysteine levels and atherosclerosis in Japan: epidemiological study by use of carotid ultrasonography.

BACKGROUND AND PURPOSE We examined whether hyperhomocysteinemia is an independent risk factor for increased carotid artery intimal-medial wall thickness (IMT) in a large, randomly selected community in Japan where the dietary habit is different and the incidence of coronary artery disease is lower compared with those of western countries. METHODS In 1111 cases (452 men, 659 women) aged 63+/-10 years old (range, 40 to 94 years) recruited from a population-based survey performed in 1999, we measured fasting plasma total homocysteine levels and performed bilateral carotid B-mode ultrasound. The participants underwent measurements of other blood chemistries (total cholesterol, HDL cholesterol, glycosylated hemoglobin A(1c), and creatinine). RESULTS For the total population, the mean total homocysteine level was 10.9 micro mol/L. Total homocysteine levels were higher in men than in women and increased with aging. With multiple linear regression analysis after adjustments for age and sex, the most powerful determinant of total homocysteine levels was serum creatinine (P<0.001). With multiple stepwise regression analysis after adjustments for age, sex, and other confounding factors, total homocysteine was significantly (P<0.05) related to IMT. Furthermore, when mean values of IMT adjusted for age, sex, and other related factors were analyzed across total homocysteine quartiles, IMT (P<0.05) showed a significant trend as total homocysteine level increased. CONCLUSIONS Plasma total homocysteine levels in Japan are similar to those reported in western countries. Mild hyperhomocysteinemia is an independent risk factor for increased carotid artery wall thickness in Japan as well.