New findings on how best to detect hypertension

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New findings on how best to detect hypertension

Posted 9-27-99
By Diane Sussman

Bethesda, Md. For years, an elevated diastolic blood pressure was the red flag for identifying patients with hypertension. But according to a new study published in the September issue of Hypertension, systolic pressure does a far better job of determining a patient's blood pressure stage and indicating the need for treatment.

"If you only know one number, the systolic blood pressure essentially conveys the risk associated with hypertension and whether the patient needs treatment," said Donald Lloyd-Jones, MD, the primary author of the study. "Diastolic blood pressure is a far less accurate measure."

Researchers from the National Heart, Lung, and Blood Institute's Framingham Heart Study examined nearly 5,000 untreated men and women and determined each person's blood pressure stage using both systolic and diastolic pressure together as recommended by national guidelines.

Researchers then compared the stage classifications with separate systolic and diastolic readings to see which came closest. They found that systolic blood pressure alone correctly classified blood pressure stages in about 96 percent of patients, while diastolic pressure alone classified only 68 percent. Among patients over 60, systolic pressure alone classified 99 percent of patients, while diastolic alone correctly classified only 47 percent.

Hypertension is diagnosed when systolic blood pressure is greater than 140 mm Hg or diastolic blood pressure is greater than 90 mm Hg. Staging is based on how high or low the blood pressure is.

The disease affects about one-quarter of American adults and is significantly undertreated, with only 68 percent of those affected aware they have the condition and only 58 percent receiving treatment, researchers say. Hypertension is a risk factor for heart disease, diabetes, and stroke.

Researchers agree that diagnosis works best when both measurements are used together, but suggest that future treatment guidelines might consider emphasizing systolic pressure.