Guidelines address 'prehypertension'. (Suggest Lifestyle Interventions).

NEW YORK -- New hypertension guidelines issued by the National Heart, Lung, and Blood Institute reflect an urgent need to intervene earlier and more aggressively to prevent high blood pressure from causing serious health consequences.

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) redefines blood pressure categories and favors diuretic-based therapy. Unveiled at the annual meeting of the American Society of Hypertension, the guidelines are based on the results of more than 30 clinical trials conducted since the previous guidelines (JNC VI) were issued in 1997.

In a bold move that has sparked considerable debate, JNC 7 defines an entirely new class of "prehypertension" that applies to patients with a systolic blood pressure of 120-139 mm Hg or a diastolic blood pressure of 80-89 mm Hg. This category includes about 45 million Americans, many of whom have previously been told that their blood pressure is normal.

Patients in this group merit attention--in the form of lifestyle-based intervention--because they face a significantly increased risk of developing hypertension and its complications, including kidney damage, cardiovascular disease, and stroke, said Dr. Aram Chobanian, dean of the Boston University School of Medicine and JNC 7 chairman.

"To put it into perspective, for every 20/10 mm Hg rise in blood pressure above 115 / 75 mm Hg, there is a doubling in risk of death from cardiovascular problems," he said.

Studies suggest that mortality rates for heart attack, stroke, and other vascular disease increase progressively starting at blood pressure levels as low as 115/70 mm Hg. Blood pressure tends to rise with age, so patients at 120/80 mm Hg at age 50 have a 90% lifetime risk of becoming hypertensive, Dr. Chobanian said. That, he said, points up the critical importance of early intervention in prehypertensive patients and aggressive intervention in hypertensive patients, especially those who have heart disease or are at high risk for heart disease, diabetes, or chronic kidney disease.

But critics of JNC 7 maintain that the guidelines fail to distinguish between etiologies of hypertension and imply that all patients will benefit from the same medications. Instead of unnecessarily creating a new group of prehypertensive patients, the critics argue, the guidelines should have focused on treatment of patients who are truly hypertensive. (See box.)