Blood pressure levels, related factors, and hypertension control status of Japanese and Americans

Blood pressure levels and related factors in Japanese, US whites and US blacks aged 30 to 74 years were compared, using data from the similarly designed national survey of each country in a similar period, i.e., the National Survey on Circulatory Disorders of Japan, 1980 (10,897 persons from all over Japan) and the second National Health and Nutrition Survey of the US, 1976 to 1980 (NHANES-II) (16,204 persons from all over the USA). Data collection methods were judged to be comparable. Data were stratified by age (30-39, 40-49, 50-59, 60-69, 70-74 yrs) and sex. Age-specific and age-adjusted mean systolic BPs of Japanese were generally higher than those of US whites; mean diastolic pressures were similar in the two populations in both men and women. Mean weight and body mass index (BMI) and their standard deviations were lower for Japanese than Americans. In US blacks, BP was higher than in Japanese or in US whites for diastolic in men, and for both systolic and diastolic in women. Systolic BP levels of black men were between those of Japanese and US whites. At specific levels of BMI, Japanese systolic BPs were markedly higher than those of US whites in all age-sex groups, and diastolic pressures were higher in Japanese than in US whites, slightly so at younger ages and more so at ages 60 and over in both sexes. The proportions of all persons with high BP who were receiving antihypertensive treatment and who were controlled were similar in most age-sex groups of the Japanese and US white populations; they were lower in US black men and higher in US black women. In linear regression analyses of BP on BMI controlled for age, slopes were similar for Japanese and Americans. However, given the lower mean BMI and smaller BMI standard deviation (less overweight), partial correlation coefficients between BMI and BP were smaller for Japanese than Americans. These results indicate that overweight plays a lesser role in Japanese than Americans in producing high prevalence rates of hypertension and that other factors are critically involved (e.g., intake of sodium, potassium, calcium, alcohol).