Impact of Diastolic and Systolic Blood Pressure on Mortality: Implications for the Definition of “Normal”

  • Brent C. Taylor
  • Timothy J. Wilt
  • H. Gilbert Welch
Original Research

ABSTRACT

BACKGROUND

The National Heart, Lung and Blood Institute currently defines a blood pressure under 120/80 as “normal.”

OBJECTIVE

To examine the independent effects of diastolic (DBP) and systolic blood pressure (SBP) on mortality and to estimate the number of Americans affected by accounting for these effects in the definition of “normal.”

DESIGN, PARTICIPANTS AND MEASURES

Data on adults (age 25–75) collected in the early 1970s in the first National Health and Nutrition Examination Survey were linked to vital status data through 1992 (N = 13,792) to model the relationship between blood pressure and mortality rate adjusting for age, sex, race, smoking status, BMI, cholesterol, education and income. To estimate the number of Americans in each blood pressure category, nationally representative data collected in the early 1960s (as a proxy for the underlying distribution of untreated blood pressure) were combined with 2008 population estimates from the US Census.

RESULTS

The mortality rate for individuals over age 50 began to increase in a stepwise fashion with increasing DBP levels of over 90. However, adjusting for SBP made the relationship disappear. For individuals over 50, the mortality rate began to significantly increase at a SBP ≥140 independent of DBP. In individuals ≤50 years of age, the situation was reversed; DBP was the more important predictor of mortality. Using these data to redefine a normal blood pressure as one that does not confer an increased mortality risk would reduce the number of American adults currently labeled as abnormal by about 100 million.

CONCLUSIONS

DBP provides relatively little independent mortality risk information in adults over 50, but is an important predictor of mortality in younger adults. Conversely, SBP is more important in older adults than in younger adults. Accounting for these relationships in the definition of normal would avoid unnecessarily labeling millions of Americans as abnormal.

KEY WORDS

blood pressure hypertension guidelines mortality 

Notes

ACKNOWLEDGEMENTS

This material received no direct funding, but is the result of work supported with resources and the use of facilities at the Minneapolis and White River Junction VA Medical Centers. The views expressed herein do not necessarily represent the views of the Department of Veterans Affairs or the United States Government.

Conflicts of Interest

None disclosed.

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Copyright information

© Society of General Internal Medicine 2011

Authors and Affiliations

  • Brent C. Taylor
    • 1
    • 2
    • 3
  • Timothy J. Wilt
    • 1
    • 2
  • H. Gilbert Welch
    • 4
    • 5
  1. 1.Department of Veterans Affairs Health Care SystemCenter for Chronic Disease Outcomes ResearchMinneapolisUSA
  2. 2.Department of MedicineUniversity of MinnesotaMinneapolisUSA
  3. 3.Division of Epidemiology and Community HealthUniversity of MinnesotaMinneapolisUSA
  4. 4.VA Outcomes GroupDepartment of Veterans Affairs Medical CenterWhite River JunctionUSA
  5. 5.Dartmouth Institute for Health Policy and Clinical PracticeDartmouth Medical SchoolHanoverUSA

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