Sequential Changes in Blood Pressure and Electrocardiographic Findings Over Seventeen Years in Three Different Regions in Okayama Prefecture

The sequential changes in blood pressure and electrocardiographic findings of populations living in three districts of Okayama prefecture, with differing environments and life styles, were analyzed during the seventeen year period from 1966 to 1982. Futhermore, factors influencing the causes of mortality among these populations were evaluated in 790 males and 1, 118 females (total 1, 908), aged from 35 to 65 years at the beginning of the survey (1966). During the survey period 94 subjects moved out of the district and 210 subjects died, so that in 1982, 975 subjects (61.1%) could be examined. Cerebrovascular disease, cancer, and cardiac disease were the major causes of death in all these districts. A higher mortality from cerebrovascular disease was recorded in the mountainous district, with harsh weather and living conditions, in contrast to the other two lowland district. There was no significant difference in mortality due to cardiac disease among the three districts. In the mountainous district, the incidence of hypertension, especially systolic hypertension, was higher than in the other two districts throughout the whole of this survey. However, after 1980, the difference in the incidence of hypertension among the districts diminished sequentially. The incidence of hypertension was higher in the elderly than in younger subjects. However, even this age difference in incidence was seen to diminish sequentially, (especially for diastolic hypertension). The ratio of the number of people who were actually treated to the population who needed hypertensive therapy increased gradually, and in 1978 there was no significant difference concerning this ratio among the three districts. Finally over 80% of the subjects who qualified for antihypertensive therapy were treated continuously. The appearance ratio of abnormal ECG findings, (Minnesota Code, Code 3, Code 3+4, 5 and especially Code 4 and 5), increased in proportion to the increase of blood pressure in the hypertensive group. The sequential appearance ratios for the borderline hypertension and stage I hypertension groups showed an inverse relationship to that of the normal group. However the appearance ratios of stage II & III hypertension groups increased sequentially with no relation to that of the normal group. Subjects whose ECG showed ST-T changes without subjective symptoms apparently increased sequentially in all districts. The incidence ratios of angina pectoris and myocardial infarction showed no si