Murray said some of the factors responsible for the worldwide increase in high blood pressure are unhealthy diets and obesity. In addition, in developing countries, more people are living in cities and getting less physical activity.
Also, the world’s population is aging, and blood pressure often increases with age, Murray explained.
“High blood pressure affects a huge number of people, and it’s getting worse. And yet, there is effective prevention through lifestyle changes and a wide array of effective medical therapies for managing blood pressure,” he said.
The number of people with systolic pressure of at least 110 to 115 mm Hg is likely to continue to increase, the study authors added.
One heart expert noted that people don’t have normal blood pressure one day and high blood pressure the next.
“The conventional thinking that there is a threshold when one goes from normal blood pressure to high blood pressure is not accurate,” said Dr. Mark Creager. He directs the Heart and Vascular Center at Dartmouth-Hitchcock Medical Center in Lebanon, N.H.
“There’s a gradual increase in risks from blood pressures that start much lower than 140 mm Hg. Even people with blood pressure lower than that need to be aware that there is an increased risk,” Creager explained.
For the study, the researchers reviewed 844 studies from 154 countries. The studies were published from 1980 to 2015 and included nearly 8.7 million people.
Over those years, the annual death rate rose from 136 to 145 per 100,000 among those with a systolic pressure of at least 110 to 115 mm Hg. Among those with systolic pressure of 140 mm Hg or more, the annual death rate increased from 98 to 106 per 100,000, the researchers found.
Most blood pressure-related deaths were caused by heart disease (5 million), bleeding in the brain (2 million), and stroke (1.5 million), the findings showed.
Five countries — the United States, China, India, Indonesia and Russia — accounted for more than 50 percent of elevated or high blood pressure cases, according to the study.
The study, funded by the Bill and Melinda Gates Foundation, was published Jan. 10 in the Journal of the American Medical Association.