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THE DECREASE IN DIASTOLIC BLOOD PRESSURE OCCURS AT A MUCH EARLIER AGE THAN INDICATED BY FRAMINGHAM

THE DECREASE IN DIASTOLIC BLOOD PRESSURE OCCURS AT A MUCH EARLIER AGE THAN INDICATED BY FRAMINGHAM

 



Author Block DW Armstrong, D Brouillard, M Matangi
Kingston, Ontario


BACKGROUND: The Framingham data regarding hypertension and age shows a progressive increase in systolic blood pressure with age. However diastolic blood pressure gradually increases until age 55 years and then progressively falls.
METHODS: CARDIOfile was searched for all 24hr ABPMs. A scattergram of age versus the 18,987 ABPMs for both systolic an diastolic blood pressure was produced. Linear regression was performed for systolic BP data points and 2nd to 4th order polynomial regression for the diastolic BP data points. The inflection point for diastolic BP was calculated using differential calculus. This is the point on the diastolic curve where the curvature sign changes. This corresponds to the age at which diastolic BP begins to decrease.
RESULTS: See Figure 1. The inflection point as described above was calculated as 42 years.
CONCLUSION: Our data indicates that the age of onset of the fall in diastolic BP occurs much earlier than is generally accepted. In fact 13 years earlier than indicated by the Framingham data. The reasons for this change are unknown at this time but could be related to the fact that Framingham is a population based study and our population is a hypertensive population. It is possible that changes in arterial stiffness may occur ealier in the hypertensive population than in the general population.