(AP) -- More American adults are aware they have high blood pressure, and more are taking medicine to try to control it, according to a new government report released Wednesday.
Yet the proportion of U.S. adults with high blood pressure has actually been holding steady at about 30 percent for a decade, the Centers for Disease Control and Prevention report found.
That finding may surprise some, given escalating hand-wringing by health officials about problems that can contribute to high blood pressure - such as obesity and salt intake.
"It may seem a little counterintuitive," said Dr. Nanette Wenger, an Emory University cardiologist who reviewed the research but was not involved in it.
She suggested a number of factors that could explain it: Perhaps more people are exercising, drinking less alcohol or taking other steps that can prevent high blood pressure.
High blood pressure - or hypertension - is often called the "silent killer" because it doesn't have symptoms, so many people don't know they have it, according to the CDC. It increases a person's chances for heart disease, stroke and other serious problems.
But it's easy to check for and usually can be controlled through exercise, diet and medicine.
The CDC report is based on detailed government health surveys done from 1999 through 2008 that included blood pressure checks. More than 24,000 adults took part in the nationwide surveys over the 10 years, said Sarah Yoon, a CDC epidemiologist who was lead author of the new report.
During that period, the percentage of adults aware of their high blood pressure increased to nearly 81 percent, from 70 percent. Most of that change was in people 45 and older and in whites and blacks.
Also, nearly 74 percent were taking medicine to control their blood pressure, up from about 60 percent.
About a quarter of Americans had high blood pressure in the early 1990s. By the end of that decade, it had reached 30 percent, but hasn't changed much since, the new study showed.
There also has been little change in the rates for men, women, whites, blacks and Mexican-Americans.
The report didn't look at why the rates have been holding steady. A CDC spokesman said there could be a connection to the nation's obesity rate. The latest CDC data indicate the obesity rate has essentially leveled off for about five years, after many years of a steady climb.
Even if high blood pressure too has plateaued, the actual number is increasing because the nation's adult population is growing - especially the baby boomer-bolstered ranks of people in their 50s and older.
The number of adults with high blood pressure grew from about 59 million to more than 66 million over the 10 years, Yoon said.
Other estimates put it at at least 74 million.
"It's nice to see we're making progress with awareness and control, but 30 percent of a big number is a very big number," said Dr. Donald Lloyd-Jones, a Northwestern University preventive medicine specialist who is a spokesman for the American Heart Association.
Lloyd-Jones and Wenger said they were perhaps most impressed by another finding: Among adults with high blood pressure, nearly half have it under control with medications, an increase from 30 percent.
That could be because cheaper generic medications are more widely available, Wenger said.
"You don't cure hypertension, you control it," she said.
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More information: CDC report: http://www.cdc.gov/nchs