Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California: blood pressure distributions.
Blood pressure measurements were made on three Japanese populations residing in Japan, Honolulu, and Northern California. A common protocol was utilized in an effort to standardize inter-observer variability. Zero terminal digit preference varied among the three areas and there was differential clustering of diastolic values at 80 mm Hg and 90 mm Hg in Hawaii and California, respectively. Diastolic blood pressure did not rise with age in any of the three populations while systolic blood pressure rose in each. Blood pressure levels in Japanese in Japan were intermediate to those in Hawaiian and Northern California Japanese, California having the higher blood pressure levels. Since the relative weights of the Japanese migrants to Hawaii and California were substantially higher than the relative weights of the non-migrant populations in Japan, the blood pressures were adjusted for these differences. When this was done, most of the differences among the various study subgroups were explained. The findings indicate that the blood pressure distributions of the Japanese populations residing in Japan, Hawaii, and Northern California cannot of themselves account for the observed differences in coronary heart disease and stroke occurrence among these populations in which there is a gradient from high stroke rates in Japan to low rates in California and a reverse trend for coronary heart disease.