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Risk of Developing Hypertension Increases with Age - 2002-02-26

A new U.S. medical study shows that ninety percent of Americans over age 55 are likely to develop high blood pressure, a condition that boosts the chances of heart disease, stroke, and kidney disease. With the move toward industrialized diets and growing prevalence of obesity around the world, this is unlikely to be just an American problem.

The message from a U.S. government study of older men and women is that the overwhelming majority of Americans can expect to develop high blood pressure by the time they are elderly.

"We were surprised to find that we found a risk of developing hypertension of 90 percent. It's an astounding figure," says physician Ramachandran Vasan, a senior researcher at the U.S. government's National Heart, Lung, and Blood Institute. He led a team that examined data from a long-term study in the city of Framingham, Massachusetts, near Boston.

Since the late 1940s, researchers have monitored 5,000 Framingham residents with blood tests and other assays, comparing the results with whether the person went on to suffer a heart attack, stroke, or other cardiovascular disease.

The latest findings, reported in the Journal of the American Medical Association, looked at data from a subgroup of 1,300 Framingham residents who were middle-aged to elderly in 1976 and tracked their health through 1998.

According to Dr. Vasan, more than half of the 55-year-old participants and about two-thirds of the 65-year-olds developed hypertension within the first decade of that period. "Individuals in our study who were age 55 or 65 and had reached that age free of high blood pressure had nine in 10 chance of developing high blood pressure during the follow-up period," he said.

For older men, the figures represent a 60 percent higher risk for hypertension than during the years 1952 to 1975. But for older women, the risk was unchanged over the earlier period. Dr. Vasan believes it has something to do with men's weight gain through the years. He notes it is no surprise that men's average weight compared to height, or body mass index, was higher in the second period, while women's had decreased slightly.

"Since weight and obesity are powerful correlates of the risk of developing hypertension," said Dr. Vasan, "we believe that the increase in the body mass index in men may be one possible explanation why we are seeing an increase in risk of developing hypertension in men in our sample, but the same thing is not evident for women in our sample."

Obesity is also increasing throughout the world, wherever countries are becoming more urbanized, using modern technology and food processing, and enjoying more leisure time. A spokesman for the American Heart Association, Johns Hopkins University cardiologist David Meyerson, says that Framingham high blood pressure findings might also apply to other nations, adding to their burden of heart and kidney disease and stroke.

"There is a wonderful Japanese study only a few years old, which demonstrated that the control of even mild levels of high blood pressure reduced the number of strokes dramatically," said Dr. Meyerson. "So I believe in all industrialized and many not-so-industrialized nations, if we can identify those people who are at risk for developing disease and get them before the disease ever develops, imagine the staggering public health benefits."

There is good news from the Framingham study. It shows that the risk of developing extremely high blood pressure has decreased. Dr. Vasan attributes this to the availability of drugs to treat it. But he warns against depending on them to keep hypertension down. "We know that high blood pressure is a preventable condition, so middle-aged individuals should adopt healthier lifestyles that are more conducive to optimal levels of blood pressure," he explains.

Dr. Vasan says this means eating moderately, avoiding a diet high in fat and salt, exercising regularly, and getting periodic blood pressure checks.