For the first time in history, global hypertension is at an all time high in low- and middle-income countries.
High blood pressure is the leading preventable risk factor responsible for disease burden worldwide. Raised blood pressure - which can result in cardiovascular disease, heart disease, stroke, and chronic kidney disease - was accountable for around 9-12 million deaths globally in 2013.
According to research published in the American Heart Association's journal Circulation, more than 30 percent of the adult population worldwide has high blood pressure, and 75 percent of those people live in low- to middle-income countries.
Previous reports have indicated that the prevalence of hypertension in low- and middle-income countries is on the rise, and is steady or decreasing in high-income countries. However, recent estimates of the differences between high blood pressure worldwide were unknown.
The aim of the new study was to gain current estimates of the worldwide burden of hypertension in low-, middle-, and high-income countries to help develop global strategies to prevent and control the condition through collaborative national and international efforts.
Data analysis involved 135 population-based studies, including 968,419 adults from 90 countries. Researchers used sex- and age-specific high blood pressure prevalence from past reports to calculate the regional and global estimates of hypertensive adults.
High-income countries significantly improved hypertension awareness
The researchers found that in 2010, 1.39 billion people worldwide were living with high blood pressure. A total of 1.04 billion of those people - almost three times the amount of high-income countries - were living in low- to middle-income countries.
In high-income countries, the greatest burden was in adults over 60 years, whereas in low- and middle-income countries, the most significant burden was in adults between 40-59 years.
Between 2000-2010, high blood pressure prevalence decreased by 2.6 percent in high-income countries, while increasing by 7.7 percent in low- and middle-income countries.
In 2010, less than half of adults with hypertension were aware of their condition. Compared with low- and middle-income countries, high-income countries had almost double the proportions of awareness (67 percent versus 37.9 percent) and treatment (55.6 percent versus 29 percent), and four times the amount of control among patients with hypertension (28.4 percent versus 7.7 percent).
Awareness (58.2 percent versus 67 percent), treatment (44.5 percent versus 55.6 percent), and control (17.9 percent versus 28.4 percent) increased substantially in high-income countries between 2000-2010.
During the same period, awareness slightly improved, from 32.3 percent to 37.9 percent, and treatment increased from 24.9 percent to 29 percent from 2000-2010. However, control worsened, from 8.4 percent to 7.7 percent, in low- and middle-income countries.
Collaboration needed to develop hypertension prevention programs
Dr. Jiang He, senior study author and researcher at Tulane University School of Public Health and Tropical Medicine in New Orleans, LA, notes that 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."
"Healthcare systems in many low- and middle-income countries are overburdened and do not have the resources to effectively treat and control hypertension," he adds. "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."
Although the majority of the world's population is represented in the study, the authors remark that more than half of the countries worldwide do not have data on the prevalence of high blood pressure. There may, therefore, be some regional and global estimate inaccuracies of adults living with high blood pressure in those countries.
"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. Collaboration is needed from national and international stakeholders to develop innovative and cost-effective programs to prevent and control this condition."
Lead author Katherine T. Mills, Ph.D., Tulane University
The study - funded by The National Heart, Lung, and Blood Institute and the National Institute of General Medical Sciences - shows that around three-quarters of people with hypertension live in low- and middle-income countries, which is likely attributed to both increasing prevalence and substantial population growth.
Although hypertension prevalence has decreased in high-income countries, it has increased in low- and middle- income countries. As a result, the prevalence of hypertension in low- and middle-income countries has surpassed that in high-income countries for the first time.