March 24, 2003 -- When it comes to high blood pressure, what you don't know can hurt you, and it turns out most older Americans know less than they should. A nationwide survey of people over 50 found that limited awareness was more of a barrier to blood pressure control than the cost of high blood pressure medications.
Although almost all of the people who answered the telephone survey had at least one blood pressure reading taken during the previous year, just over half knew their blood pressure numbers. And only about one in four said they had high blood pressure - a far lower incidence that would be expected for the age group. Nine out of 10 people 55 and older develop hypertension.
"Many health providers say things like your blood pressure is normal or only a little elevated, without giving patients the numbers," lead researcher Brent M. Egan, MD, tells WebMD. "We would encourage people to ask what their reading is and to write it down on a card along with the date of their measurement."
A person is considered to have high blood pressure if their systolic (top) number is 140 mm Hg or higher and/or their diastolic (bottom) number is 90 mm Hg or higher -- except for diabetics in whom a lower blood pressure reading is recommended (130/80). The systolic blood pressure is the pressure of blood in the artery when the heart contracts. The diastolic reading measures the resting pressure in between beats.
It is now recognized that the systolic reading is the more important determinant of cardiovascular risk, but Egan and colleagues found that 30% of those with systolic readings of 140 mm Hg or higher did not understand that they had high blood pressure. And three-quarters of the respondents believed that their diastolic reading was the most significant number. The survey is published in the March 24 issue of the journal Archives of Internal Medicine.
"Levels of diastolic blood pressure have been the focus of concern among physicians for many years; all of the clinical trials on hypertension define end points based on diastolic blood pressures," Yale University high blood pressure expert Marvin Moser, MD, wrote in an accompanying editorial. "It is not unexpected, therefore, that the general public still believes that the diastolic blood pressure determines risk."
Moser tells WebMD that patients are not the only ones to underestimate the importance of high blood pressure. Many doctors, he says, are still reluctant to put older patients with moderately elevated systolic pressure on medication because they often complain of feeling weak or dizzy at the goal of 140 mm Hg. In the telephone survey, 40% of patients said their doctors did not recommend treatment unless systolic blood pressure was higher than 160 mm Hg.
"The clinical trials tell us that older patients tolerate [high blood pressure] medication as well as younger ones, but in the real world physicians hear from older patients every day who tell them they just don't feel well on medication. That is why many doctors don't try to lower pressure to goal."
But, he says, even a modest drop in systolic pressure can dramatically reduce the risk of stroke and heart failure among elderly patients. Lowering blood pressure gradually also helps patients adjust and avoid dizziness and weakness, he says.
"Most elderly patients require medication to get their blood pressure to goal, and for almost all that should include a diuretic," Moser says, adding that combining a diuretic with an ACE inhibitor or beta-blocker is the best treatment approach for older people with high blood pressure.