Elsevier

Annals of Epidemiology

Volume 9, Issue 2, February 1999, Pages 101-107
Annals of Epidemiology

Original reports
Relationship of Blood Pressure to Cardiovascular Death: The Effects of Pulse Pressure in the Elderly

https://doi.org/10.1016/S1047-2797(98)00034-9Get rights and content

Abstract

PURPOSE: To investigate the relationship of systolic and diastolic blood pressure to fatal myocardial infarction, fatal stroke and other death related to cardiovascular diseases (CVD).

METHODS: The study was based on a prospective longitudinal study conducted by the Veterans Administration at the Boston Outpatient Clinic. Participants are male volunteers from the greater Boston area. Main outcome measures are fatal myocardial infarction, fatal stroke and other deaths related to cardiovascular diseases. The method of pooled logistic regression was used for statistical analysis.

RESULTS: For younger men (age 21–59), after adjusting for effects of other risk factors, when systolic and diastolic blood pressure were considered separately, SBP was predictive of cardiovascular death (SBP: RR = 1.23; 95% CI = 1.05, 1.45 per 10 mmHg of increase), and DBP showed a nonsignificant positive trend in relation to cardiovascular death (DBP: RR = 1.27; 95% CI = 0.95, 1.69 per 10 mmHg of increase). For older men (age 60–85), when SBP and DBP were considered separately, SBP (RR = 1.26; 95% CI = 1.02, 1.55 per 15 mmHg of increase) was directly related, but DBP (RR = 1.05; 95% CI = 0.83, 1.32 per 8 mmHg of increase) was not related to cardiovascular death. However, for the elderly group, when SBP and DBP were considered jointly in the regression model, then the regression coefficient of DBP (β = −0.018, p = 0.30) was of approximately the same absolute magnitude as that of SBP (β = 0.021, p = 0.02) but opposite in sign. For younger men, when SBP and DBP were considered jointly, SBP (β = 0.021, p = 0.049) but not DBP (β = −0.001, p = 0.953) was positively related to cardiovascular death.

CONCLUSIONS: We found that, for the elderly, pulse pressure (SBP-DBP) may be a more accurate predictor of cardiovascular death than either SBP or DBP alone. The relative risk per 35 mmHg of increase of pulse pressure, which equals the approximate interval from the 10th to the 90th percentile in the elderly group, is 2.1 with 95% CI = 1.1, 3.8. In younger subjects, SBP, but not DBP, is an independent predictor of fatal CVD.

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.

Section snippets

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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