Original reportsRelationship of Blood Pressure to Cardiovascular Death: The Effects of Pulse Pressure in the Elderly
Introduction
Abnormal blood pressure has long been recognized as a major risk factor for the development of coronary artery disease, stroke, and other cardiovascular disease (CVD) outcomes in adults 1, 2. Isolated systolic hypertension is recognized as an important predictor of adverse cardiovascular events in the elderly 3, 4, 5, 6. Isolated systolic hypertension is known to predict myocardial infarction (MI), stroke, and death from congestive heart failure 7, 8. In a previous analysis (9) of the Normative Aging Study (NAS) data, we noticed that while the mean systolic blood pressure (SBP) increased with age for all age groups, the mean diastolic blood pressure (DBP) increased with age only prior to age 57.5; after age 57.5 the DBP decreased by 1–2 mmHg per decade of age. This phenomenon of decreasing DBP for the elderly also has been reported by the Manitoba follow-up study (10) and the Framingham study (11). Therefore, pulse pressure, defined as SBP minus DBP, increases slowly up to age 60 but then rises rapidly with increasing age.
In this paper, we discuss the use of pulse pressure, in comparison to SBP or DBP alone, in predicting fatal myocardial infarction, fatal stroke and other deaths related to CVD in the elderly. Other risk factors considered include age, body mass index (BMI = Weight/Height2), cholesterol level (mg/dl), diabetes, prior MI, prior stroke, and smoking status. The study cohort of the NAS consists of initially healthy men with age range initially between 21 to 80 in 1963. Risk factors were recorded at each visit from 1963 to 1992.
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Study Population
The NAS (2) is a longitudinal study of health and aging established by the Veterans Administration (VA) at the Boston Outpatient Clinic in 1963. Community residents from around the greater Boston area were contacted and volunteered to be screened according to specific health criteria, and those with chronic health conditions including asthma, chronic bronchitis, obesity, diabetes mellitus, and hypertension were excluded. The study cohort initially included 2280 community-dwelling male
Demographic Data
Of the selected study participants, the age distribution at their baseline visits has a range from 20 to 80. The mean actual age at each subject’s initial visit is 43 years old with a standard deviation of 10.32. When the study began, 77% of subjects were 25–49 years old, 17% were 50–59 years old, and 6% were 60–79. Except for one person who had eight visits, subjects have up to seven visits. Over 80% of subjects have two or more visits. At the baseline visit, 33% of the subjects were former
Discussion
We utilized the method of pooled logistic regression to analyze longitudinal data concerning the relationship of SBP and DBP and other cardiovascular risk factors to fatal CVD in the NAS. We found that there was a significant effect of pulse pressure in predicting fatal cardiovascular outcomes in the elderly (age 60 and up). Conversely, for persons under age 60, only systolic blood pressure was a significant predictor of fatal CVD.
In a previous analysis (9) of the NAS data set we noticed that
Acknowledgements
The research is supported in part by grant HL-40619 of the National Institutes of Health. The Normative Aging Study is sponsored by the Health Services Research and Development Service of the Department of Veterans Affairs. We thank Dr. Stanley Franklin for helpful comments and Soma Datta for programming assistance.
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