Prehypertension among middle-aged and elderly people in Taiwan: A five-year follow-up

Abstract

Aim: To evaluate the prevalence of prehypertension among middle-aged and elderly people in Taiwan and to explore the evolutionary changes of blood pressure in 5-year follow-up period. Methods: In 2000, people aged over 40 participating in annual health examinations at local health stations in I-Lan County were invited to join the study. Past medical histories were reviewed, physical examinations and serial laboratory tests were performed for participants. All participants were followed in 2005 by a medical record review, telephone survey or personal visit. Subjects with prehypertension were sorted for further analysis. Results: Overall, 1053 people (mean age = 64.4 ± 11.4 years, 44.4% males) were enrolled in the primary cohort. The prevalence of hypertension and prehypertension was 40.4% and 35.8%, respectively. In 2005, 677 subjects (mean age: 68.8 ± 10.4 years, 42.5% males) were successfully followed, which revealed a significant increase of systolic blood pressure (3.7 ± 16.8 mmHg, p<0.001), but not diastolic blood pressure (0.3 ± 11.5 mmHg, p = 0.758) in prehypertensive subjects; however, both systolic blood pressure (14.3 ± 17.4 mmHg, p<0.001) and diastolic blood pressure (7.7 ± 13.3 mmHg, p<0.001) were significantly increased among normotensive subjects. The cumulative incidence of prehypertensive subjects becoming hypertensive was 31.3%, and those who became hypertensive were significantly older (65.3 ± 8.6 vs. 62.2 ± 12.3 years, p = 0.024), having higher pulse pressure in 2000 (49.6 ± 10.6 vs. 45.1 ± 11.6 mmHg, p = 0.001), serum total cholesterol (214.3 ± 31.7 vs. 204.0 ± 37.2 mg/dL, p = 0.020) and low-density lipoprotein-cholesterol (141.7 ± 29.2 vs. 132.7 ± 34.7 mg/dL, p = 0.042). Conclusions: The prevalence of prehypertension among older Taiwanese was 35.8% and the 5-year cumulative incidence of hypertension from prehypertension was 31.3%. Older prehypertensive subjects with higher pulse pressure, higher serum total cholesterol and higher low-density lipoproteincholesterol were more likely to become hypertensive within 5 years.