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High BP prevalence nearly doubled worldwide in 40 years

Due to population growth and aging, the number of people with elevated BP has risen substantially worldwide, from 594 million people in 1975 to more than 1.1 billion people in 2015, according to a comprehensive analysis by the NCD Risk Factor Collaboration published in The Lancet.

“High [BP] is the leading risk factor for stroke and heart disease, and kills around 7.5 million people worldwide every year. Most of these deaths are experienced in the developing world,” Majid Ezzati, PhD, lead researcher from Imperial College London, said in a press release.

Ezzati and colleagues conducted a pooled analysis of 1,479 population-based studies that included adults aged 18 years and older (n = 19.1 million) from 200 countries who had their BP measured. Trends in mean systolic and diastolic BP from 1975 to 2015, and the prevalence of high BP was assessed through a Bayesian hierarchical model. The impact of population growth and aging on the prevalence of increased BP levels, defined as systolic BP of 140 mm Hg or higher, or diastolic BP of 90 mm Hg or higher, was calculated.

Results showed that in 2015, the global age-standardized mean systolic BP for men and women was 127 mm Hg and 122.3 mm Hg, respectively. The mean diastolic BP was 78.7 mm Hg and 76.7 mm Hg, respectively. In addition, the global age-standardized prevalence of high BP in 2015 was 24.1% and 20.1% in men and women, respectively.

Mean systolic and diastolic BP significantly decreased in high-income western and Asia Pacific countries in the past 4 decades. As a result, these countries, which in 1975 had some of the highest BP levels, have some of the lowest worldwide BP levels. Canada, the United Kingdom, the United States, Peru, South Korea and Singapore had the fewest number of adults (1 in 8 women and 1 in 5 men) with elevated BP in 2015. People living in South Korea and Canada had the lowest systolic BP levels (men, 118 mm Hg; women, 111 mm Hg)

The highest BP levels were seen in several central and eastern European, sub-Saharan Africa and south Asia countries. More than a third of men in Croatia, Latvia, Lithuania, Hungary and Slovenia and about a third of women in Niger, Chad and Mali have increased BP.

In addition, more than half of all adults living with raised BP (n = 590 million) lived in east, southeast and south Asia, mostly in India (n = 199 million) and China (n = 226 million) in 2015. Central and eastern Europe, sub-Saharan Africa, central Asia and Oceania had the highest average age-corrected systolic BP in 2015 (Slovenian men: 138 mm Hg; Nigerian women: 133 mm Hg).

Overall, there was a reduction in the prevalence of high BP in high- and middle-income countries, though it remained unaffected elsewhere. In addition, most regions showed higher BP levels in men compared to women.

According to the researchers, population growth and aging directly affected the worldwide surge in the number of adults with high BP levels. The decrease seen in some countries was because of declining age-specific prevalence.

“Taken globally, high BP is no longer a problem of the Western world or wealthy countries,” Ezzati said in the release. “It is a problem of the world’s poorest countries and people. Our results show that substantial reductions in BP and prevalence are possible, as seen in high-income countries over the past 40 years. They also reveal that WHO’s target of reducing the prevalence of high BP by 25% by 2025 is unlikely to be achieved without effective policies that allow the poorest countries and people to have healthier diets—particularly reducing salt intake and making fruit and vegetables affordable—as well as improving detection and treatment with BP lowering drugs.”

In an accompanying editorial, Kazem Rahimi, from the George Institute for Global Health at the University of Oxford, England, suggests that collaborative, multisectoral, national efforts are required to effectively control BP levels in less successful countries while expediting the declines in more successful regions.

“The failure to tackle this issue more decisively will come at a high cost, particularly to disadvantaged individuals and societies,” he added. “The clear view of recent achievements, as provided by the NCD Risk Factor Collaboration, should help us to collectively steer the action plan more effectively and equitably towards decreasing BP globally.” – by Alaina Tedesco

Disclosure: Ezzati reports funding by Wellcome Trust. Rahimi reports not relevant financial disclosures.