New Definition Means Almost Half the World's Adult Population Now Hypertensive

July 13, 2018

Levels of hypertension in developing countries appear to be similar to those in the United States according to the new American College of Cardiology (ACC)/American Heart Association (AHA) definition of blood pressures above 130/80 mm Hg, a new study suggests.

"With the old JNC-7 [Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure] definition of 140/90 mm Hg, the prevalence of hypertension in developing countries was lower than in the US, but with this new definition there doesn't seem to be much difference across different parts of the globe, with hypertension affecting almost half the world's population," lead author Gulam Muhammed Al Kibria, MBBS, University of Maryland, Baltimore, told Medscape Medical News.

However, he noted, the new definition of hypertension may have a limited impact in the developing world.  

"Most people in developing countries never have their blood pressure measured, so all these new people now classified as hypertensive will probably not be identified," Kibria said.

However, the message that almost half the population is now hypertensive may spur governments to do more about raising awareness of this issue and implementing lifestyle advice.

"Because of limited resources, the health systems in developing countries has not focused on preventative care for chronic conditions like hypertension. And with the old definition of hypertension, the condition was less prevalent than in the West so not given a priority. 

"However, with this new definition it suggests that hypertension is just as big a problem in developing countries as it is in the West, and more needs to be done to tackle it," he added.

The study is published online July 13 in JAMA Network Open.

Prevalence Doubles

The researchers wanted to look at the prevalence of hypertension in developing countries according to the new definitions in the ACC/AHA guidelines.

They selected Nepal because unlike the situation in most developing countries, some reliable data on blood pressure were available, and they believe Nepal is representative of many other developing countries in South Asia and Africa.

The researchers used data from the population-based 2016 Nepal Demographic and Health Survey conducted in 2016-2017, in which more than 14,000 individuals from across the country had their blood pressure measured.

Investigators found that 44.2% had hypertension according to the 2017 ACC/AHA guideline compared with 21.2% per the old JNC-7 definition.

"So the new definition was associated with an absolute increase of 23% and a more than doubling in numbers of people classified as hypertensive," Kibria said.  

A similar study in the United States found that the prevalence of hypertension has risen from 31.6% according to the old JNC-7 definition to 45.6% with the new 2017 ACC/AHA definition, the authors note.

"Considering the morbidity and mortality associated with hypertension, this condition is a major public health challenge for Nepal and other countries with similar sociodemographic characteristics," the investigators write.

"Our results signify the importance of implementing more awareness programs to control hypertension as well as minimizing complications associated with hypertension. In addition, similar research in other countries could be helpful to estimate country-specific burdens of hypertension," they conclude.

Far-Reaching Consequences

In an accompanying commentary, David A. Watkins, MD, University of Washington, Seattle, notes the study raises important questions about allocation of scarce resources to treatment of hypertension in low-income countries.

He writes that the main implication of the findings for public health in Nepal and other low-income countries may be to "approach the ACC/AHA guideline with caution, particularly because it has such far-reaching consequences for primary health care systems that are already overburdened."

Watkins told Medscape Medical News that it's worth questioning whether it's appropriate "to have such a low bar for hypertension in poor countries where health resources are so limited."   

"This new definition of hypertension is more relevant to the Western world, where there are more resources available to direct towards the low-risk patients identified with systolic pressures of 130 to 140 mm Hg.

"Nepal and other developing countries have far more pressing priorities for their healthcare resources than identifying patients with moderately elevated blood pressure."

However, he added that these latest figures suggest there is a "breathtaking transition" underway in South Asia, with numbers of people with hypertension now similar to the United States. 

"This will hopefully stimulate some action to develop primary care programs to first identify those with higher blood pressure who are at high risk of heart disease and stroke. Then in time these programs could broaden to include the lower-risk patients captured by the new hypertension definition."

JAMA Network Open. Published online July 13, 2018. Full textCommentary

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