Low diastolic ambulatory blood pressure is associated with greater all-cause mortality in older patients with hypertension

Abstract

Objectives: To assess the relationship between office and ambulatory systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP) and total mortality in elderly patients with hypertension.

Design: Observational prospective cohort study.

Setting: Hypertension outpatient clinic in a geriatric academic hospital.

Patients and methods: Eight hundred five older (> or =60) subjects with hypertension underwent office and ambulatory BP measurement. Mortality was assessed after a mean follow-up of 3.8 years.

Results: In a total of 3,090 person-years of follow-up, 107 participants died (average mortality rate 3.5% per year). With bivariate analysis, participants who died had higher SBP and PP and lower DBP, with office and ambulatory measurements. Mortality rates were greater with higher SBP and lower with higher DBP. As a combined effect of these trends, PP was associated with the widest death rate gradients, from 12 to 66, 13 to 63, and 9 to 70 per 1,000 person-years across office, 24-hour, daytime, and nighttime PP quartiles, respectively. Multivariate Cox analysis confirmed these trends; the adjusted hazard of death increased linearly with increasing ambulatory SBP and PP, whereas it decreased significantly with increasing ambulatory DBP. A five times greater risk of death was detected when comparing night-time PP quartile 4 (median PP value 78 mmHg) with quartile 1 (median PP value 46 mmHg).

Conclusion: In older patients with hypertension, low DBP and high PP, particularly when measured using ambulatory BP monitoring, are associated with greater risk of death. The achievement of an SBP treatment goal should not be obtained at the expense of an excessive DBP reduction.