At 78 percent among people aged 50 and over, South Africa has the highest rate of high blood pressure reported for any country in the world, at any time in history. And less than 10 percent of people are effectively controlling their condition with medication, according to an analysis of data from the Study on Global Ageing and Adult Health (SAGE) conducted by the World Health Organisation (WHO), which surveyed more than 35,000 people aged 50 and over in South Africa, China, Ghana, India, Mexico and Russia. 

High blood pressure increases people's risk of experiencing stroke, heart disease and other forms of serious illness, with those over the age of 50 at significantly increased risk. In the past, it was associated with rich, developed countries or with wealthier sectors of society. Today, high blood pressure is a condition that affects the majority of society, rich or poor, rural or urban. Rates for women are consistently higher.

The findings were presented today in South Africa by Peter Lloyd-Sherlock, professor of social policy and international development at the University of East Anglia (UEA). The work aims to fill a crucial gap in understanding about the prevalence, awareness, possible causes and treatment of high blood pressure, the leading cause of death globally for low- and middle-income countries.

Lloyd-Sherlock and co-authors warn of potentially "catastrophic" consequences for people's health and well-being if global and national efforts to tackle the impact of high blood pressure are not transformed immediately. They say the rates of hypertension in low- and middle-income countries are striking and that levels of treatment and control are inadequate, despite half those sampled being aware of their condition.

"In many countries public awareness about hypertension remains very low, and the condition is not prioritized by national governments or development agencies. Unless this changes quickly, avoidable deaths and disability resulting from hypertension are set to soar. Interventions should include awareness raising, prevention and treatment. Ideally, we should persuade people to adopt healthier diets and lifestyles, but in the short run we should at least ensure they have access to effective treatment," said Lloyd-Sherlock.   

Those who took part in the SAGE survey were categorized as hypertensive if the mean of two measurements was equal or greater than 140mmHg (systolic blood pressure) or 90mmHg (diastolic blood pressure), or if they were taking treatment for hypertension. The rates of high blood pressure ranged from 78 percent in South Africa to 32 percent in India.

In all six countries, national prevalence was strongly associated with age and weight. India achieved the highest rate of treatment effectiveness (55 percent); the lowest rate of condition control was in Ghana (four percent); the lowest treatment effectiveness was in Russia (17 percent), which had the second highest rate of hypertension (71 percent). South Africa had the highest rates for the 'lifestyle' risk factors of obesity (45 percent) and low physical activity (59 percent).

In South Africa the study involved 3,820 people. Only 38 percent of those who tested positive for hypertension were aware of their condition. Most people who were aware were on treatment, but it was only effective in 24 percent of cases. The authors say limited awareness and ineffective treatment were why only eight percent of people with hypertension had their condition under control, compared to a rate of 14 percent in India, the highest of the six countries studied. For poorer people living in rural districts rates of control were particularly low.