LONDON: The number of adults living with hypertension worldwide has doubled over the past 30 years, with most of this increase occurring in low- and middle-income countries, according to a study published in The Lancet journal.
The international team of researchers analysed blood pressure measurements from more than 100 million people aged 30-79 years taken over three decades in 184 countries.
They found that the number of people with hypertension rose from an estimated 331 million women and 317 million men in 1990 to 626 million women and 652 million men in 2019.
Despite being straightforward to diagnose and relatively easy to treat with low-cost drugs, nearly half of people with hypertension worldwide in 2019 were unaware of their condition, the researchers said.
Also more than half of women (53 per cent) and men (62 per cent) with the condition were not treated, they said.
"Despite medical and pharmacological advances over decades, global progress in hypertension management has been slow, and the vast majority of people with hypertension remain untreated, with large disadvantages in low- and middle-income countries," said Professor Majid Ezzati, Imperial College London, UK, the senior author of the study.
"Our analysis has revealed good practice in diagnosing and treating hypertension not just in high-income countries but also in middle-income countries," Ezzati said.
The authors noted that large improvements in treatment and control rates seen in some middle-income countries show that the expansion of universal health coverage and strengthening primary care have been instrumental in improving high blood pressure care.
High blood pressure is directly linked to more than 8.5 million deaths worldwide each year and is the leading risk factor for stroke, ischaemic heart disease, other vascular diseases, and renal disease.
Lowering blood pressure can cut the number of strokes by 35-40 per cent, heart attacks by 20-25 per cent, and heart failure by around 50 per cent.
Hypertension was defined as having systolic blood pressure of 140 millimeters of mercury (mm Hg) or greater, and diastolic blood pressure of 90 mm Hg or greater, or taking medication for high blood pressure.
The amount of pressure in the arteries during the contraction of heart muscle is called systolic pressure.
The blood pressure when the heart muscle is between beats is called diastolic pressure.
Modelling was used to estimate prevalence of hypertension and the proportion of people with hypertension who had a previous diagnosis, were taking medication for hypertension, and whose hypertension was controlled to below 140/90 mm Hg, by country, year, and age.
The global age-standardised prevalence of hypertension in adults has remained largely unchanged over the past 30 years -- with around a third of the adult population worldwide living with hypertension in 1990 and 2019, the researchers said.
The rates have dropped sharply in high-income countries, but have increased or remained unchanged in many low- and middle-income countries (LMICs), especially those in Oceania, they said.
Canada and Peru had the lowest proportion of people living with hypertension in 2019 at around 1 in 4, according to the study.
Taiwan, South Korea, Japan, and some countries in western Europe including Switzerland, Spain, and the UK had the lowest hypertension rates in women, while Eritrea, Bangladesh, Ethiopia, and the Solomon Islands had the lowest rates in men.
At the other extreme, more than half of women had hypertension in Paraguay and Tuvalu in 2019, and over half of men in Argentina, Paraguay, Tajikistan and several countries in central and eastern Europe, the researchers found.
Treatment and control have improved in most countries since 1990, with particularly large improvements seen in high-income countries like Canada, Iceland, and South Korea, they said.
However, there has been little change in LMICs in sub-Saharan Africa and Oceania, Nepal, and Indonesia.
"Low detection and treatment rates that persist in the world's poorest nations, coupled with the rising number of people who have hypertension, will shift an increasing share of the burden of vascular and kidney diseases to sub-Saharan Africa, Oceania and south Asia," said study co-author Leanne Riley from WHO, Switzerland.
"Improving the capacity of these countries to detect and treat hypertension as part of primary health care and universal health coverage must be accelerated," Riley added.
The authors noted that while the study provides the first comparable estimates of blood pressure prevalence, diagnosis, treatment and control in adults for all countries of the world, it may be affected by a lack of data in some countries, especially in Oceania and sub-Saharan Africa.