Hypertension is a rising global health problem. An estimated one billion people live with what is more commonly known as high blood pressure. Of these, more than nine million die from the condition each year.
When hypertension is not treated properly, sufferers develop cardiovascular diseases such as strokes, heart attacks or kidney failure.
Cardiovascular diseases—and particularly hypertension—have traditionally been diseases associated with an ageing population. It mainly affects people over the age of 40.
In Africa these diseases have tracked the wave of “western” lifestyle practices sweeping across the continent: rapid urbanisation and people indulging in bad diets with fast foods and little to no exercise. On top of this, Africa faces a unique challenge. As anti-retroviral treatment is rolled out to everyone living with HIV, and general improvements in health care take place, life expectancy is increasing. The incidence of hypertension is therefore likely to rise. It’s projected that 75% of older people will be hypertensive in low and middle income countries by 2025.
But few large studies have explored hypertension in Africa. Anecdotal evidence collected by researchers suggest the actual burden of the disease is poorly understood: people don’t know that they suffer from the condition and therefore don’t seek treatment.
We set out to establish whether people knew they had the condition and if they did, whether they controlled their blood pressure. We did a survey in four countries: Burkina Faso, Ghana, Kenya and South Africa, looking at both rural areas and the peri-urban settings in the cities of Nairobi and Johannesburg.
Our study shows hypertension is a critical health problem in Africa. The picture it paints is that there are stark differences in the prevalence, awareness and control of high blood pressure on the continent. Ultimately there is a need for regionally tailored intervention.
Although hypertension can easily be detected by routinely measuring blood pressure, the reality is that across the regions studied, up to half of the population are unaware of their condition. And of those who are aware, up to half of them show poor control through treatment.
We found that some parts of the continent are worse than others. In South Africa, for example, up to 50% of the people between the ages of 40 and 60 suffered from high blood pressure. In rural Burkino Faso though, there was only a 15% prevalence.
In addition, there were also stark difference in different settings in the same countries. And in some areas despite treatment being high, people’s blood pressure was not under control, raising questions about the effectiveness of their treatment and how well they stuck to drug regimens.
It shows that health promotion needs to be improved to increase awareness but more importantly that better access to care, and infrastructural changes to existing primary health care facilities are required for treatment to improve, and for it to be adhered to.
As part of our survey we measured the blood pressure of people between the ages of 40 and 60 from rural areas in east, west and South Africa as well as two peri-urban areas in the cities of Nairobi and Johannesburg.
Hypertension rates were low in West Africa, higher in East Africa. Prevalence ranged from 15% in West Africa to 25% in East Africa, and between 42% and 54% in South Africa.
There are many reasons for these different rates.
East Africa, which has lower levels of hypertension, could be at this point because it is in the early phases of the epidemiological and health transition. But the risk here is that as people gain more access to fast foods, and live more sedentary lifestyles, hypertension rates could spurt.
South Africa on the other hand has the highest prevalence of hypertension on the continent. Diets are rich in refined and fast foods, lifestyles are sedentary, and obesity is a norm. It also has the largest number of people whose blood pressure is still not controlled despite them being on treatment.
In addition to the differences in hypertension rates across the continent, there were other differences too. Gender is one example.
Only 40% of the men who suffered from hypertension were aware of their condition. And of those who were aware and on treatment, only 39% had controlled blood pressure.
Women, however, were more aware of their condition (54%) than men and just over half of those undergoing treatment had controlled blood pressure. This is a common observation that’s common in many studies of hypertension across the continent.
Why there is this difference between men and women is unclear. One answer could be related to the higher levels of employment of men, who will subsequently have limited access to health care outside of their working hours.
Assessing the burden on the continent is challenging because of the paucity of data on hypertension from different African countries. But our study provides actual baseline data for older adults. The next step is to engage with these participants in five years again in a follow up study.
This will help us assess the main drivers and consequences of hypertension in the different regions. At that point we will examine how many new cases of hypertension have arisen and interrogate the health status and genetic background of participants with long standing hypertension. We will be able to evaluate how these changes may be related to the environment.
Most importantly though non-communicable diseases, including hypertension, must be prioritised and managed to reduce the public health burden and to avert a new epidemic on the African continent.
Stuart Ali, Researcher at the Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, and AWI-Gen Project Manager, University of the Witwatersrand and Francesc Xavier Gomez-Olive Casas, Research Manager at MRC/Wits Agincourt Research Unit, University of the Witwatersrand