Q&A: Africa’s high blood pressure problem


An estimated one billion people around the world have high blood pressure, which is a leading risk factor for non-communicable diseases such as stroke and heart disease. Nowhere is the problem more prevalent than in Africa, where 46 percent of adults have the condition, according to WHO.

Thomas Gaziano is a trained cardiologist and assistant professor at Harvard Medical School and Harvard School of Public Health. Thirteen years ago, Gaziano said serendipity or providence brought him and his wife, also a physician, to South Africa, where he saw first-hand the high burden of non-communicable diseases. Gaziano has focused on cardiovascular disease in resource-poor settings ever since.

Below, Gaziano talks with GlobalPost about Africa’s blood pressure problem and the major challenges to addressing it.

Thomas Gaziano

Q: The World Health Organization recently marked World Health Day with an awareness campaign around high blood pressure. This is the same public health problem the agency drew attention to in 1978. What’s changed in the last 35 years?

A: Overall, globally, there are about 900 million to maybe a billion people without fully controlled blood pressure. It’s the single largest risk factor for morbidity and mortality globally. Hypertension clearly is a significant challenge.

Probably no more than 5 percent of those 900 million people have their blood pressure properly controlled or at the goal that most of the international guidelines recommend, having a blood pressure below 140 systemic and 90 diastolic.

Even in the US, anywhere from 25 to 35 percent of our population is controlled. So, we’re not doing perfectly well. But globally it’s probably less than 5 percent.

Q: Is that because people in the developing world don’t know they have a problem?

A: In order for us to improve blood pressure, we have to: number one, increase awareness — i.e. detection or diagnosis. Number two, once we have people aware, we have to either initiate treatment with medications or institute lifestyle changes. And three, we have to achieve control over it. Most of these low- and middle-income countries are behind in all three of those areas.

Q: Why is high blood pressure most prevalent in Africa?

A: As a caveat, the data for Africa are probably the worst for any other global region. Some low- and middle- income countries have started to [track the health of their population], either through the Demographic Health Survey or through WHO STEPS, which is starting to measure these kinds of these risk factors. But they’re only just beginning in many of these low- and middle- income countries.

The number of people that are on treatment is much lower in Africa than in any other part of the world, based partly on poverty and access to medications.

There’s a study suggesting that a country like Malawi, the number of days of a person’s income to pay for a month’s worth of medication… is 18 days. In some other places it’s seven, nine, 10 days. That’s just not sustainable. Most of these are out-of-pocket costs for people in these countries where there isn’t global health insurance. Or anywhere near it.

It’s both the cost of medication and access to medications. And then awareness — detection and screening — in these populations. In many of them, the health care systems are still devoted to acute care or urgent care at the health centers, and not geared for long-term primary care and detection of things like blood pressure.

Q: What leads to higher blood pressure?

A: We can still find populations in Africa, interestingly enough, or other aboriginal populations, globally, where blood pressure levels at age 65 are still 90 over 60, which is a normal blood pressure.

In the western world, the trend is to see blood pressure increasing with aging, and that’s related to environmental things, such as decreased exercise, increased weight, and increased salt intake.

As these African populations move from say, the Maasai and the fields of Kenya into the cities like Nairobi, their blood pressures skyrocket when they get exposed to salt, they stop exercising, and they start to gain weight.

Those are the major contributors in any developed or developing society – it’s the decrease in fruit and vegetable intake, which is good for blood pressure, an increase in obesity, and an increase in sodium from salt, preserved foods, and processed foods.

Q: You have taught a freshman seminar at Harvard called “The Burden of Cardiovascular Disease in the Developing World: A Silent Epidemic.” How have non-communicable diseases and their risk factors become “silent” epidemics in the developing world?

A: Hopefully it’s less silent now. Many of the low- and middle- income countries were not aware of the problem in their own countries. They still, and, appropriately, have concern for maternal and child health concerns, diarrheal diseases, HIV/AIDS—particularly in southern Africa and eastern Africa. It really wasn’t high on their radar screen. The thought was that since high-income countries had this, it must be something related to affluence. That, on some levels is true. You have to stop dying from infectious diseases, accidents, violence or things that occur at a young age.

One of the contributors for cardiovascular disease is living beyond the age of 40 or 45. Once you start to do that, if you have enough financial resources to buy cigarettes, or to buy fast food, and you start moving from rural centers into urban centers, and taking factory jobs or other jobs that don’t require as much physical activity, then these risk factors start to present themselves.

It’s much cheaper to get cigarettes, fast food and things like that now than it was 50 years ago. So even poorer people can have them, even if the country is not fully economically developed.

In some of the countries, it’s no longer silent, they’re waking to it. Others are still not sure that this is the problem they need to be dealing with.

Q: What are the biggest challenges to adequately addressing the problem of high blood pressure in the developing world?

A: We need to improve our detection. People have this debate over whether there should be more population-based interventions or individual treatment. I think both are necessary. Population strategies regarding all these factors include changes in tobacco control. With regards to the other risk factors and lifestyle, I think efforts to reduce sodium intake… are useful, increasing the availability of fruits and vegetables will certainly [help], and finding ways to improve physical activity.

On the medical side of things, we could improve simplified detection. We’re looking in South Africa and other countries, using community health workers, people with even less training than nurses, [to see] if they are able to do detection of people with risk factors. We look at global risk – we don’t want to know just their blood pressure. Are they obese? Do they have diabetes? Do they smoke? If they have multiple risk factors, then we recommend that they get referred to a local community health center. 

We have simplified strategies identifying people with high risk, of treating people with low blood pressure costs. We’ve just got to figure out how to do it now in these lower resource settings.

It’s not about determining what causes heart disease or what are the best medicines, it’s how we get it to people. It’s a more health systems-related challenge, a health delivery challenge. It’s not just about understanding what is wrong but how do we implement what we do know is right. 

(Interview has been condensed and edited for clarity.)

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