A new study has found that people who are native to South Asian countries of India, Pakistan, Bangladesh, Sri Lanka, and Nepal are at a higher risk of heart attacks due to factors like smoking and developing diabetes at a younger age.

The study, which appears in the January 17 issue of JAMA, found that these South Asian countries account for about a quarter of the world's population and contribute the highest proportion of cardiovascular diseases compared with any other region globally.

Government Medical College, Nagpur, MD Prashant Joshi led a team of researchers in an attempt to determine the reasons for the higher rates of coronary heart disease in native South Asians compared with individuals from other parts of the world.

The study included 1,732 heart attack patients from 15 medical centres in 5 South Asian countries and 10,728 heart attack cases from other countries.

The researchers found that the average age for first heart attack was lower in South Asian countries (53.0 years) than in other countries (58.8 years), largely due to the lower prevalence of protective risk factors such as leisure time physical activity, regular alcohol intake, and daily intake of fruits and vegetables.

They also noted that some harmful factors were more common in native South Asians than in individuals from other countries: history of diabetes, current and former smoking, history of hypertension, psychosocial factors such as depression and stress at work or home, and elevated ApoB/ApoA-I ratio (a protein/lipid).

When stratified by age, South Asians had more risk factors at ages younger than 60 years.

The authors stated that the study showed that South Asians this susceptibility for acute myocardial infarction (AMI; heart attack) suggest that lifestyle changes are necessary to substantially reduce the risk of heart attacks.

"The younger age of first AMI among the South Asian cases in our study appears to be largely explained by the higher prevalence of risk factors in native South Asians. These data suggest that lifestyle changes implemented early in life have the potential to substantially reduce the risk of AMI in South Asians," the authors state.