High blood pressure, number of deaths increasing worldwide
An international analysis of nearly 9 million people states that the rate of high blood pressure (hypertension) and elevated blood pressure (prehypertension) jumped between 1990 and 2015.
"There are almost 900 million people in the world with hypertension, and there are almost 3.5 billion people with elevated blood pressure that doesn't quite meet the definition of hypertension," said study lead author Christopher Murray. He directs the University of Washington's Institute for Health Metrics and Evaluation in Seattle.
"Blood pressure is the leading cause of premature death and disability in the world," Murray said.
Blood pressure is made up of two numbers. The top number, called systolic pressure, measures the pressure in the arteries when blood is being pumped from the heart. The bottom number, the diastolic pressure, measures pressure between heartbeats. Blood pressure is expressed in millimeters of mercury (mm Hg).
The study authors said that even systolic blood pressure within what is considered a normal range - less than 120/80 mm Hg, according to the American Heart Association - can increase the risk of heart attack and stroke.
In the study, systolic blood pressure of 110 to 115 mm Hg was considered elevated, while 140 mm Hg and higher was considered high blood pressure.
According to study co-author Dr. Gregory Roth, the researchers chose to look at blood pressures at 110 to 115 mm Hg - well below the clinical definition of high blood pressure - because this is where the risk of high blood pressure begins.
"The definition of hypertension is a systolic pressure greater than 140 mm Hg. However, there is very strong evidence that the risk of having an elevated blood pressure begins above 115 mm Hg," said Roth, an assistant professor of cardiology at the University of Washington in Seattle.
What's lacking is evidence that people with blood pressure between 115 and 140 mm Hg should be taking medications to lower it. There are other ways to control blood pressure, including healthy lifestyle choices and maintaining a normal weight, Roth said.
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.
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