Major Studies of Heart Disease in South Asia


By Geeta Anand

It’s been well-documented that South Asians seem to suffer a higher risk of cardiovascular disease than Westerners.

Agence France-Presse/Getty Images
A group of scientists from University of Cambridge are trying to find the reasons behind the high risk of cardiac diseases in South Asia.

Now a group of scientists at the University of Cambridge are conducting two large-scale population studies in Bangladesh and Pakistan that they hope will tell us why.

The risk is bad enough for residents of high-income countries, for whom cardiovascular disease is the most common cause of death and disability. But the rate of death from the disease is falling in the West, where the risk factors are well-known—blood fats, high blood pressure, diabetes and smoking.

In contrast, the incidence of death and disability from the disease are soaring in South Asia. Manifested in heart attacks and strokes, the disease has been on the rise in South Asians for the past three decades.

Though the same risk factors likely apply to South Asians, there are many theories on why people from the subcontinent suffer a particularly high rate of the disease, from sedentary lifestyles to the fat, called ghee, in which many dishes are cooked.

But nobody knows for sure.“The study of vascular disease among people living in South Asia has been comparatively neglected,” John Danesh, head of the Department of Public Health and Primary Care at the University of Cambridge, said in a press release this week.

He says there have been only a few studies designed to “evaluate the distinctive genetic, biochemical and lifestyle risk factors affecting this group.”

Dr. Danesh and a group of scientists at the University of Cambridge are hoping their study will help them to better understand the unique risk factors affecting these populations.

The Pakistan study, with 35,000 participants, had its origins several years ago when the co-lead investigator, Danish Saleheen, was a medical student in Pakistan. With colleagues in Pakistan, Dr. Saleheen began investigating whether local dietary practices, such as the cooking in ghee, and non-cigarette-based ways of consuming tobacco, including chewing and sniffing it, were to blame. He included cultural habits, such as marrying first cousins, and environmental influences, such as contaminants in food and water, as risk factors evaluated in the study.

After he moved to Cambridge in 2006, Dr. Saleheen secured funding and improved the design of the study with Dr. Danesh. The study now recruits 10,000 patients a year from 13 institutes across Pakistan.

The study has contributed to the discovery of nine genes for coronary artery disease and six separate genes of type 2 diabetes, according to the University of Cambridge.

“We are beginning to identify distinctive factors which increase the risk of, or protect against, heart diseases,” said Dr. Saleheen, in the Cambridge press release.

“For instance, consumption of ghee and indigenous types of tobacco, including ‘naswar,’ increases the risk of heart attack,” he said.

The Bangladesh study, begun in January as a pilot, aims to enroll 1,000 patients by year-end.

In the late 1990s, it was estimated there would be a 100% increase in cardiovascular disease across South Asia by 2020. But Bangladesh already has experienced a 3,500% increase since then, says Rajiv Chowdhury, the Bangladeshi doctor who is heading the study along with physician Emanuele Di  Angelantonio.

Dr. Chowdhury says the study aims to build an epidemiological resource to test current and future hypotheses on risk factors to shape local and global disease preventative practices.

“Bangladesh has the highest rate of urbanization and population density in South Asia and is facing the worst threats of climate change globally,” Dr. Chowdhury said. These “extraordinary circumstances,” he says, may have influenced the population’s massive propensity to suffer from cardiovascular disease.

In an interview with India Real Time, Dr. Angelantonio said he believes poor nutrition and environmental contaminants may have made the population more vulnerable to the disease—in addition to genetic markers, as yet to be identified.

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