Objective: To study the natural populations studied including 3 groups of workers, 6 groups of farmers and 1 group of fishermen, distributed in Heilongjiang, Hebei, Shanxi, Shannxi, Jiangsu and Zhejiang provinces and Guangxi Autonomous Region.
Methods: In 1982-1985, a total of 25656 persons (male 13,390, female 12,266) aged 35-59 were surveyed for the risk factors of cardiovascular diseases.
Results: 20641 (male 10584, female 10057) of them were re-examined in 1988-1989, giving a response rate of 80.5%. During the 5 year follow-up period, the incidence of definite hypertension was 1.20% (male) and 1.07% (female), with the borderline plus definite rates being 3.27% and 2.68% per year, respectively. The incidence varied from 0.76% to 5.62% per year for borderline plus definite. The incidence was higher in the north than in the south, higher in farmers than in workers, and lowest in fishermen. The incidence rates were higher in men than in women, and the older the age, the higher the incidence of hypertension. Both univariate and logistic regression indicated that the main risk factors of hypertension are the levels of baseline systolic and diastolic blood pressure, BMI, and alcohol intake, all of which showed a dose-response relation to the incidence rate of hypertension. These relationships were affected by age; the younger, the more marked the increase of relative risk (RR) with risk factor levels. After adjusting for age, sex and location by logistic regression, with every 10 mmHg increase of SBP or DBP within the normotensive range, or every 1 unit increase of BMI, the RR of hypertension was -- estimated to increase by 71.5%, 102.4% and 10.8%, respectively. No significant relationship was found between the level of serum cholesterol and the incidence of hypertension, but persons with faster heart rates showed a higher RR.
Conclusion: Primary prevention of hypertension in persons should be started before age of 35 years.