In order to investigate the effect of cold circumstances on hypertension and its complications, this epidemiologic study, prospectively to cover a ten year period, was started in 1977 on 996 subjects in the relatively cold town of“Tanno”, T-Cho, and on 1000 subjects in the relatively warm town of“Sobetsu”, S-Cho, in Hokkaido, Japan, who range in age from 40 to 64. Measurements of blood pressure, height, body weight, the index of obesity and skinfold thickness, laboratory tests of blood and the gulcose tolerance test have been performed in the early morning following overnigth fasting. The results of this study in the first year were as follows. 1) Participant rates in T-Cho and S-Cho were 99.7 and 99.8%, respectively. 2) Systolic blood pressure, β-lipoprotein and blood urea nitrogen in the summer in T-Cho, and systolic and diastolic blood pressure in the winter and the index of obesity, skinfold thickness, total cholesterol, total protein, fasting blood sugar and the cardio-thoracic ratio in the summer in S-Cho were significantly higher when compared with results in the other town. 3) Incidences of hypertension and borderline hypertension defined by the criteria of WHO were 21.3 and 19.9%, respectively, (total 41.2%) in T-Cho and 24.3 and 15.7%, respectively, (total 40.0%) in S-Cho in the summer, and 20.2 and 21.6%, respectively, (total 41.8%) in T-Cho and 28.1 and 16.6%, respectively, (total 44.7%) in S-Cho in the winter. 4) The prevalence rate of hypertension obviously increased with age in both towns. 5) The greatest range of individual blood pressure was 120-129mmHg in systole and 80-89mmHg in diastole in both towns. 6) The mean value of blood pressure, and the incidence of hypertension and borderline hypertension in T-Cho were almost equal between the summer and the winter, whereas those in S-Cho increased in the winter. 7) Cases in which over 20% was observed on the index of obesity were noted in 23.5% of the subjects in T-Cho and 28.8% of those in S-Cho. 8) Incidences of cases with≥231mg/dl in total cholesterol, ≥451mg/dl in β-lipoprotein, ≥171mg/dl and≤70mg/dl in triglyceride, ≥21mg/dl in blood urea nitrogen and≥7.0mg/dl in uric acid were 11.2, 27.7, 14.0, 27.4, 13.8 and 12.3% in T-Cho and 13.3 19.6, 14.3, 14.9, 8.4 and 12.0% in S-Cho, respectively. 9) 45.1% of the subjects in T-Cho and 56.3% in S-Cho showed an abnormal glucose tolerance, and these incidences increased with age. However, most abnormalities remained of borderline type. 10) The incidences of cases with a cardio-thoracic ratio of more than 50% and with abnormal electrocardiograms were 27.3 and 31.1%, respectively, in T-Cho and 36.6 and 31.7%, respectively, in S-Cho.
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