Individuals with “Prehypertension?,” blood pressure readings on the high end of normal, have an increased risk of having a major cardiovascular event, according to a report in the Annals of Family Medicine.

In May 2003, the Joint National Commission on High Blood Pressure introduced prehypertension as new risk category. The condition was defined as having a systolic blood pressure - the top number - between 120 and 139 mm Hg or a diastolic pressure - the bottom number - between 80 and 90 mm Hg.

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.

SOURCE: Annals of Family Medicine, July/August 2005.