Background and purpose: The significance of isolated systolic hypertension (ISH) has been well documented, particularly in the elderly. However, isolated diastolic hypertension (IDH) has not been formally recognized as a unique hypertension entity. This study compared the ages of onset and characteristics of ISH and IDH.
Methods: The Cardiovascular Disease Risk Factors Two-Township Study (CVDFACTS) is an ongoing longitudinal study of the risk factors for and pathogenesis of cardiovascular disease in two Taiwanese townships, Chu-Dung (a Hakka community) and Pu-Tzu (a Fukienese community); participating patients were included in our study. Among the 3,357 subjects who were aged at least 20 years, free of hypertension, and had complete data at baseline, 2,374 subjects were followed. The average duration of follow-up was 3.23 years and the follow-up rate was 71%. Data regarding smoking, alcohol consumption, health and socioeconomic background, blood pressure, and body mass index were collected. Clinical and hemostatic profiles were assessed.
Results: ISH (systolic blood pressure, SBP > or = 140 mmHg and diastolic blood pressure, DBP < or = 90 mmHg) incidence increased with age in general (men: 0 per 1,000 person-years at age 20-34 yr, 1.9 at age 35-49, 14.3 at age 50-64, 40.9 at age 65-74, and 73.3 at age 75+ yr; women: 0 per 1,000 person-yr at age 20-34 yr, 3.6 at age 35-49, 17.8 at age 50-64, 64.9 9 at age 65-74, and 33.5 at age 75+ yr), but peak incidence of IDH (DBP > or = 90 mmHg and SBP < or = 140 mmHg) occurred between 35 and 49 years (men: 8.9 per 1,000 person-yr at age 20-34 yr, 14.5 at age 35-49, 12.3 at age 50-64, 2.7 at age 65-74, and 0 at age 75+ yr; women: 1.7 per 1,000 person-yr at age 20-34, 4.2 at age 35-49, 3.7 at age 50-64, 0 at age 65-74, and 0 at age 75+ yr). Significant predictors for ISH were older age (men: hazard ratio, HR = 8.25 at 45-64 yr and HR = 22.91 at 65+ yr; women: HR = 34.11 at 45-64 yr and HR = 97.98 at 65+ yr), diabetes (HR = 2.57) and elevated fibrinogen (HR = 1.49) in men, and shorter clotting time in women (HR = 1.23). Significant predictors for IDH were elevated body mass index (men: HR = 4.03; women: HR = 7.4), and higher glucose (HR = 1.46) and uric acid concentrations (HR = 1.94) in men.
Conclusions: The results of this study indicate that ISH and IDH have different age incidence patterns and predictors, and suggest that the pathogenesis of ISH and IDH may be different.