Franklin's team analyzed blood pressure data on nearly 20,000 patients who took part in the National Health and Nutrition Examination Survey, which was conducted by the National Institutes of Health from 1988 to 1994. They found that 24 percent of the survey's participants had hypertension, regardless of whether they were being treated for it. Of the participants with hypertension, more than three-quarters were 50 or older. Normal blood pressure is considered to be less than 140 millimeters over 90 millimeters when measured with a blood pressure device. The researchers found that among participants aged 50 and older, about 80 percent had systolic blood pressure higher than 140 but had diastolic pressures below 90.
Diastolic readings measure blood pressure when the heart is at rest.
Systolic readings measure pressure when the heart contracts to pump blood through the body. The researchers think that high systolic pressure may be left untreated because most doctors assume that higher diastolic pressure indicates a greater risk of heart disease than systolic pressure. But since so many patients had uncontrolled blood pressure regardless of treatment, the researchers suspect that systolic pressure may play a greater role in hypertension than previously assumed. We think that if more attention were paid to systolic pressure as patients get older, we might see fewer people who are at a higher risk for heart disease and stroke. The UCI study is part of Franklin's ongoing research on cardiovascular disease, currently the leading cause of death in the United States.