- According to the World Health Organization (WHO), 80% of premature heart disease and diabetes and 40% of cancer is preventable.1 The landmark INTERHEART Study reiterates and reinforces the crucial role of a handful of risk factors that when modified through lifestyle and medication could drastically reduce the burden of CAD (coronary artery disease) in India.2 This case-control study compared heart attacks in 52 countries, representing every inhabited continent (15152 with and 14820 without heart attack).3
- The increased CAD risk in South Asians reflects an adverse combination of gene-environment interactions. The prevalence of major modifiable risk factors is high and is increasing in India. In sharp contrast, the prevalence of these risk factors is similar or lower in the Indian Diasporas (Asian Indian Paradox) and is decreasing albeit slowly.
- In the INTERHEART Study, the mean age of first heart attack was six years lower in South Asians than in participants from other countries (53 vs 59 years) consistent with the numerous studies showing premature CAD in this population (see Prematurity).
- This study identified 9 modifiable risk factors (6 harmful and 3 protective) that are responsible for 90% of the heart attacks worldwide. These include abnormal lipids, smoking, diabetes, high blood pressure, abdominal obesity, psychosocial factors, low fruit and vegetable consumption, low alcohol consumption, and low physical activity. The same risk factors were equally important for South Asians.2
- In this study, Asian Indians and other South Asians had a very low prevalence of protective CVD (cardiovascular disease) factors such as regular physical activity and fruit and vegetable consumption. In sharp contrast they had a higher prevalence of harmful risk factors such as abnormal lipids, diabetes, and abdominal obesity.2
- Given that just two simple factors (tobacco and abnormal lipid ratio) explain more than two thirds of risk, targeting tobacco, diet, and physical activity may have huge implications for the Indian population.4
- Regular alcohol consumption was protective in non-South Asians, but not so in South Asians, possibly because of different drinking patterns in the two populations. Asian Indians in general do not consume alcohol regularly, but those who do, often indulge in harmful binge drinking.2
- The latest report from the INTERHEART study has shown that family histories of heart disease can double the risk conferred by the 9 modifiable risk factors. It appears that Asian Indians have a national history of heart disease mediated through genetically elevated levels of lipoprotein(a). Studies are underway to delineate the role of this enigmatic lipoprotein in India and Pakistan.5
- The Prospective Urban and Rural Epidemiological (PURE) study, involving 28,500 people from 5 locations in India and 36,500 people from Bangladesh and Pakistan, will provide further insight into the proximal cause of obesity, diabetes, and CVD risk factors in South Asians attributable to urbanization. The first paper on the subject is due in September 2011.
1. World Health Organization. Preventing Chronic Disease: A Vital Investment World Heath Organization, Geneva 2005. 2005.
2. Joshi P, Islam S, Pais P, et al. Risk factors for early myocardial infarction in South Asians compared with individuals in other countries. Jama. Jan 17 2007;297(3):286-294.
3. Yusuf S, Hawken S, Ounpuu S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet. Sep 11 2004;364(9438):937-952.
4. Ajay VS, Prabhakaran D. Coronary heart disease in Indians: implications of the INTERHEART study. Indian J Med Res. Nov 2010;132(5):561-566.
5. Chow CK, Islam S, Bautista L, et al. Parental history and myocardial infarction risk across the world: the INTERHEART Study. J Am Coll Cardiol. Feb 1 2011;57(5):619-627.