Epidemiology of isolated systolic hypertension in PuLi, Taiwan

The clinical significance of isolated systolic hypertension (systolic blood pressure ≧ 160 mmHg and diastolic blood pressure < 90 mmHg) has long been recognized, but its prevalence and correlates have not been well characterized. A community-based study was carried out by the Yang-Ming Crusade in 1987-1988 in PuLi Town, Taiwan. Of the 2573 registered residents over 30 years old, 1738 were interviewed, and their fasting blood samples were drawn and tested. The prevalence of isolated systolic hypertension was 2.1%. Age-specific prevalence increased with age. No significant difference was found between men and women. No trend was found at the urbanizational level. To study the significant correlates of isolated systolic hypertension, univariate analyses were applied first. Stratified analyses by age and by sex were used for interaction assessment. Based on the above findings as well as from the clinical point of view, logistic regression was used for multivariate analyses. Logistic regression analysis showed that after controlling the covariates simultaneously, four variables were significantly correlated with isolated systolic hypertension: age (≧ 50 vs. < 50 years, OR = 3.4, 95% CI = 1.6-7.2); diabetes (yes vs. no, OR = 2.4, 95% CI = 1.2-4.7); blood urea nitrogen (≧ 25 vs. < 25 mg/dl, OR = 2.1, 95% CI = 1.2-3.9); and physical activity (frequent vs. infrequent, OR = 1.8, 95% CI = 1.0-3.1). In comparison with definite (≧ 160 95 mmHg) and borderline ( 140 90- 160 95mmHg) hypertension as defined by WHO, the different sets of predictors and the possible adverse effect of frequent physical activity on isolated systolic hypertension were found and discussed.