DALLAS, August 8, 2016 -- For the first time in history, people living in low- and middle-income countries have a higher prevalence of hypertension - or high blood pressure - than people living in high-income countries, according to new research in the American Heart Association's journal Circulation.

A 2010 data analysis involving more than 968,000 participants from 90 countries found that more than 30 percent of adults worldwide live with high blood pressure, and 75 percent of those adults live in low- and middle-income countries.

Hypertension is a major risk factor for heart disease and stroke as well as the leading preventable cause of premature death and disability worldwide. Past reports have shown that the prevalence of hypertension is increasing in low- and middle-income countries while it is steady or decreasing in high-income countries, but recent estimates of this global disparity are unknown.

In this study, researchers used sex- and age-specific high blood pressure prevalence from 131 past reports to calculate the regional and global estimates of hypertensive adults.

Researchers found:

In 2010, 31.1 percent (1.39 billion) of the adult population worldwide had high blood pressure, 28.5 percent (349 million) of adults in high-income countries and 31.5 percent (1.04 billion) of adults in low- and middle-income countries.

High blood pressure prevalence decreased by 2.6 percent in high-income countries while increasing 7.7 percent in low- and middle-income countries between 2000 and 2010.

In high-income countries, significantly improvements were noted from 2000 to 2010: awareness increased from 58.2 percent to 67.0 percent, treatment rates improved from 44.5 percent to 55.6 percent and control increased from 17.9 percent to 28.4 percent.

In low- and middle-income countries, awareness slightly improved from 32.3 percent to 37.9 percent and treatment increased from 24.9 percent to 29.0 percent from 2000 to 2010, but control worsened from 8.4 percent to 7.7 percent.

There are many reasons for these global disparities.

"Aging populations and urbanization, which is often accompanied by unhealthy lifestyle factors, such as high sodium, fat and calorie diets and lack of physical activity, may play an important role in the epidemic of hypertension in low- and middle-income countries," said Jiang He, M.D., Ph.D., senior study author and researcher at Tulane University School of Public Health and Tropical Medicine in New Orleans, Louisiana.

"Healthcare systems in many low- and middle-income countries are overburdened and do not have the resources to effectively treat and control hypertension," He said. "In addition, because hypertension is symptomless and many people in low- and middle-income countries do not have access to screenings or regular preventative medical care, it is often underdiagnosed."

Researchers noted that most of the world's population is represented in the study, but more than half of the countries worldwide didn't have data on hypertension prevalence, so there may be some inaccuracies in their regional and global estimates of adults living with high blood pressure.

"Hypertension needs to be a public health priority in low- and middle-income countries to prevent future cardiovascular and kidney disease, and associated costs to society," said Katherine T. Mills, Ph.D., lead author and researcher at Tulane University. "Collaboration is needed from national and international stakeholders to develop innovative and cost-effective programs to prevent and control this condition."

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Co-authors are Joshua D. Bundy, M.P.H.; Tanika N. Kelly, Ph.D.; Jennifer E. Reed, M.P.H.; Patricia M. Kearney, M.D., Ph.D.; Kristi Reynolds, Ph.D.; and Jing Chen, M.D. Author disclosures are on the manuscript.

The National Heart, Lung, and Blood Institute and the National Institute of General Medical Sciences funded the study.

Additional Resources:

Blood pressure images are located in the right column of this release link http://newsroom. heart. org/ news/ for-the-first-time-in-history-high-blood-pressure-is-more-common-in-lower-income-countries?preview= e8ebdf0933ecdf01ca9b05798d7cf32e

After August 8, view the manuscript online here.

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