Re-evaluating prevalence of risk factors for cardio-vascular disease among people in extreme poverty

A new study debunks the conventional belief that CVD is low among the poor; major risk factors including diabetes, hypertension, smoking have a significant prevalence across all sections, regardless of income, experts say

Updated - March 15, 2024 02:47 pm IST

Published - March 14, 2024 10:55 pm IST

Among those living in extreme poverty who should be taking a statin for secondary prevention of CVD, only 1.1% were on the drugs.

Among those living in extreme poverty who should be taking a statin for secondary prevention of CVD, only 1.1% were on the drugs. | Photo Credit: Getty Images

It has conventionally been assumed that prevalence of cardiovascular disease (CVD) risk factors among those living in extreme poverty in low and middle-income countries (LMICs) is low. 

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There are, of course, reasons for this: Historically, this group has been thought to take in fewer calories and have correspondingly lower body mass index, consume a largely plant-based diet and be in occupations associated with higher physical activity. All of these lifestyle patterns we know, decrease the risk of developing CVD and its risk factors. But there is very little data available on the prevalence of CVD risk factors among those living in poverty. A recent paper in Nature Human Behaviour by Pascal Geldsetzer et al, lists all of the above, but goes on to deliver results from a study that busts that assumption.

Assumptions not necessarily true

The findings of a global study, have established that the assumptions are not necessarily true any more. Researchers pooled individual-level data from 105 nationally representative household surveys across 78 countries, representing 85% of people living in extreme poverty globally, and sorted individuals by country-specific measures of household income or wealth to identify those in extreme poverty. CVD risk factors (hypertension, diabetes, smoking, obesity and dyslipidaemia) were present among adults in extreme poverty. Most were not treated for CVD-related conditions, particularly hypertension. 

The authors say: “Understanding the extent to which this assumption of a low prevalence of CVD risk factors among those in extreme poverty holds true is important for setting priorities within health policy and care delivery, both for equity and effectiveness. From an equity perspective, if CVD risk factors mostly affect wealthier population groups in LMICs, then investing in programmes aimed at preventing and treating CVD instead of focusing on those conditions that disproportionately affect those in extreme poverty could further worsen health inequities by wealth.

Poverty level was as stratified by World Bank country income category. Extreme poverty is generally defined by the international poverty line of $1.90 per day, and to enable comparison with other income groups in LMICs, researchers also examined the prevalence of CVD risk factors for the population with an income <$3.20 and <$5.50 per day, as well as those with an income >$5.50 per day. 

In the analysis, they discovered that the prevalence of hypertension was similar between these poverty level groups and those with higher income levels. They found that among participants living in extreme poverty, only diabetes was associated with differential prevalence by whether they lived in an urban centre or in rural areas, with urban dwellers at higher risk; men had a slightly higher prevalence of hypertension and a far higher prevalence of smoking than women. For diabetes, the prevalence was not statistically different between income categories in low-income countries or upper middle-income countries; only in lower middle-income countries did there exist a clear gradient wherein those with higher incomes had a higher prevalence of diabetes. 

The prevalence of obesity displayed a positive income gradient across all World Bank country categories. The prevalence of smoking and dyslipidaemia (abnormal lipid levels) was low across poverty levels in low-income countries and high across population income groups in upper middle-income countries, with an income gradient in the prevalence in lower middle-income countries. These are all known factors predisposing individuals to a high risk of cardio vascular disease.

Poor lack access to medicine

What was equally or more significant is that among those living in extreme poverty and who had hypertension, only 15.2% reported taking blood pressure (BP)-lowering medication and 5.7% had achieved hypertension control (BP < 140 mmHg/ < 90 mmHg). Of those poor living with diabetes, 19.7% reported taking blood glucose-lowering medication. Among those living in extreme poverty who should be taking a statin for secondary prevention of CVD according to WHO guidelines, only 1.1% were on the drugs. In low-income countries, hypertension treatment and control, diabetes treatment and statin use were low across poverty levels. 

“This is an important study, “says J. Amalorpavanathan, vascular surgeon, and member, the Tamil Nadu State Planning Commission. “The conventional belief that CVD is low among the poor is no longer valid. The major risk factors of CVD like Diabetes, Hypertension, Smoking etc have a significant prevalence across all sections, regardless of income. We also know that the health systems’ engagement of poorer sections with these diseases is abysmal. As a Lancet study revealed, this group adds substantially to the suffering and mortality of the poorest billion in the world.”

The authors state that the study estimating CVD risk factor prevalence among adults living in extreme poverty would provide a crucial empirical foundation for future work and addresses the call of the The Lancet NCDI Poverty Commission for “investigation regarding a broad range of priority NCDIs … with an additional focus on the rural poor”. One of the authors of the study and professor of global health, at the Institute for Applied Research, Birmingham University, Justine Davies says: “We recommend that governments put in place programmes to detect people with these risk factors that are targeted at poorer people. These may involve doing education, awareness, and screening programmes in areas where the government knows that socio-economically deprived people live. It is then important that once detected, people are referred to care and that care is accessible to them in terms of geography, costs, and overcomes other cultural or educational barriers that people who are less well-off often need to overcome.”

Mitigation initiatives

Some nations have some sort of scheme to address the issue in a limited sense. For instance, India has a National Programme for prevention & Control of Cancer, Diabetes, Cardiovascular Diseases and Stroke and State governments have further added on with their own regional surveillance and intervention programmes. For instance, Tamil Nadu has a scheme wherein intervention for non communicable diseases is delivered at the door step of the patients. It is crucial to evaluate these schemes from time to time to ensure that they are addressing the target audience effectively.

“Tamil Nadu’s ‘Makkalai Thedi Maruthuvam’ scheme is specifically designed to address this important gap in the health care system,” Dr. Amalorpavanathan further explains. Under the scheme, since 2001, more than one crore people have been visited at their homes. About 1.50 crore people regularly receive drugs for hypertension, and 1.08 crore people get drugs for diabetes. “It is too early to comment about the long term control but data is being collected regularly for analysis. We shall certainly embark upon research to identify the relation between poverty and CVD and its contributive factors and effective ways to address them,” he says.

Dr. Davies adds: “It is really important to do so, to see if they are effective at detecting people with risk factors and treating these in people who have them, but also for prevention in those who don’t yet have the risk factors. As part of these effectiveness studies, it is also important to understand why the programme might or might not have worked, so it can be adjusted in order to improve effectiveness if needed.”

Dr. Amalorpavanathan also says a key shortcoming in communicating the hazards of smoking is the lack of vigorous public education. The poor seem to outnumber the rich in smoking, which is a major risk factor for diabetes. “We must include education, to see if it has a modifying role in the community. The government of Tamil Nadu and the State Planning Commission will certainly undertake this research,” he adds.

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