Chicago ? Half of the 70 million Americans with high blood pressure are keeping it under control by taking medication, meeting a government goal set a decade ago and reducing their risk of life-threatening health problems, a study suggests.

Almost one in three adults has high blood pressure. In 1988, only about 27 percent of them kept it under control. By 2007-08, that number had climbed to 50 percent, according to the study in today’s Journal of the American Medical Association.

The findings “should be cause for celebration,” although more work needs to be done, said Dr. Aram Chobanian of Boston University, who was not involved in the study.

Millions of Americans still have uncontrolled high blood pressure, which can raise a person’s risk of heart attack, stroke and kidney failure. And the prevalence of the disease is increasing.

Many people require more than one drug to reduce blood pressure. For some, cost and lack of access to physicians is also an issue.

The new analysis compared several government health surveys since 1988. About 10 years ago, the government set goals for preventing high blood pressure and reducing the number of people who have it but are unable to control it.

The first goal — to reduce the number of people with high blood pressure — fell short, according to a preliminary report released in December.

High blood pressure prevalence increased to about 29 percent in 2007-08. The new analysis shows the second goal, controlling the condition, was achieved.

“We’re doing a better job of treating, but we’re not improving it in the first place,” said lead author Dr. Brent Egan of the Medical University of South Carolina.

Egan has worked as a paid consultant and speakers bureau member for companies that make high blood pressure medicine. He said that work is unrelated to his research for the study, which was paid for with federal and state grants.

The study authors analyzed periodic national health surveys involving almost 43,000 people. Participants were asked if they had been diagnosed with high blood pressure and if they were taking medication to lower it.

Blood pressure was measured during physical exams. Readings less than 140 over 90, the usual cutoff for high blood pressure, were considered controlled.

Participants who reached that goal used medication, Egan said.

In a JAMA editorial, Chobanian said a wider variety of medicines to treat high blood pressure without major side effects, including cheaper generic options, contributed to the success.

Lifestyle changes such as losing weight and getting exercise also can reduce blood pressure. But the study results suggest not a lot of people are making those changes.

Researchers found that among Americans with high blood pressure, more than 46 percent are obese and nearly 20 percent have diabetes — rates that are higher than in the general population and have increased substantially since 1988.

Chobanian said more aggressive efforts are needed on prevention, including improving American diet and exercise habits.