Blood pressure: lower is better

Filed in archive Studies on July 28, 2005

Lower is indeed better. A new class - "prehypertension" - was introduced in the most recent Joint National Commission on High Blood Pressure: 120 to 139 millimeters of mercury systolic (top number) or 80 to 90 diastolic (bottom number).

A recent study links this state to adverse cardiovascular events:

Dr. Heather A. Liska, from the Medical University of South Carolina in Charleston, and colleagues analyzed data from nearly 9,000 subjects who participated in the National Health and Nutrition examination Survey I between 1971 and 1975. The subjects were followed for 18 years for major cardiovascular events.

Individuals with prehypertension had a 32 percent increased risk of cardiovascular disease. One or more cardiovascular risk factors were noted in 93 percent of those with prehypertension.

Further analysis showed that only the highest pressures in the prehypertension category raised the risk of cardiovascular disease. For example, a systolic pressure of 130 to 139 mm Hg or a diastolic pressure of 85 to 89 mm Hg increased the risk by 42 percent compared with those normal blood pressure levels, whereas lower prehypertensive pressures did not have a significant effect.

By comparison, subjects with overt hypertension had more than double the risk of having a major cardiovascular event compared with those with normal blood pressure, the investigators point out.

"With current knowledge alone, prehypertension should serve as an early warning system for patients and clinicians that metabolic changes which ultimately lead to cardiovascular disease may well be underway," Liska's team concludes.

("High Blood pressure may lead to cardio event -study", Reuters, Jul.26)