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The special section on Coronary artery disease in Indians (Curr Sci, 25 June 1998) addressed a rapidly emerging epidemic of non-communicable diseases. With infections on the downtrend due to a combination of medical and socioeconomic factors, non-communicable diseases are becoming dominant in developing countries such as India.
Asian Indians are now a focus of special interest in macrovascular disease research. They are prone to vascular disease at an earlier age, and are affected more virulently. But conventional risk factors such as generalised obesity, hypertension and dietary habits cannot easily explain the increased risk.
What then could be responsible for this virulence ? Insulin resistance, abnormalities of Lp(a) levels and lower levels of physical activity in Asian Indians were postulated (1). The evidence is not unequivocal for any of these. Nor can they readily account for the high rates of diabetes mellitus in emigrant Indians (2).
It must be stressed that coronary artery disease (CAD) is not an isolated event. It is the end result of a host of risk factors, nature and nurture, known and unknown. What is important is that most of these are silent, and tend to increase with westernisation, in terms of life style attitudes and stresses. As a corollary, they can be corrected prevented or at least altered.
Common sense suggests that healthy eating habits and healthy life-style maintenance protect against CAD. It is sobering that they did not, as shown in the Coronary Artery Disease in Asian Indian (CADI) Study (3). However we must still ensure that risk factors are prevented and corrected (especially smoking, sedentary lifestyle, high blood pressure), without sliding down to therapeutic nihilism.
Reaven popularised the concept of metabolic syndrome-X, comprising of dyslipidemia, hypertension, coronary artery disease, glucose intolerance and insulin resistance (4). Asian Indians are prone to adult onset diabetes mellitus (type 2 diabetes), and are projected to be among the largest ethnic group with diabetes early in the next century (5).
A hypothesis to explain pathogenesis of CAD in Asian Indians was proposed: genetic susceptibility, perhaps with anomalies of lipoprotein (a), along with lifestyle alterations, lead to insulin resistance, abdominal fat deposition, hyperinsulinemia and high prevalence of diabetes mellitus. These in turn are associated with increased thrombotic tendency, with elevated levels of plasminogen activator inhibitor-1 and decreased tissue plasminogen activator, ultimately leading to excess CAD (6).
These common non-communicable diseases demand time, effort and expense in management from the individual, the physician and the social system (7). A small proportion of individuals are identified, and an even smaller proportion present to medical attention.
I looked at the prevalence of potentially modifiable risk factors in a cohort of individuals with diabetes mellitus from our computerised database. Between December 1992 and July 1998, there were 8959 registered individuals with the diagnosis of diabetes mellitus (5638 males, 3321 females). Nearly a fourth of them were known hypertensives and 5% had known ischemic heart disease. About 20% men were current smokers. About 50% men and 90% women were sedentary (Table 1).
Even though the risk factors alone may not explain adverse events, it is essential we attempt to correct them. Impaired glucose tolerance is a biochemical diagnosis, with a proportion of individuals progressing to frank diabetes. In an earlier study on impaired glucose tolerance (IGT), we showed that modifiable risk factors such as hypertension, smoking, alcohol use and sedentary habits were equally common in individuals with IGT and with age and sex matched newly diagnosed diabetics (8). Implying again that healthy lifestyle must be maintained in this group of 'pre-diabetic' individuals.
It was hypothesised that stress could be the underlying factor in the development of a cluster of metabolic abnormalities, leading to central obesity and other components of 'syndrome-X' (9). Published studies have shown that yoga resulted in improved glycemic control in individuals with diabetes mellitus (10) .
In conclusion, non-communicable diseases are beginning to catch up with infectious diseases in Asian Indians. CAD and diabetes mellitus occur earlier and in a more virulent form compared to the West. The prevalence of conventional risk factors alone cannot account for this anomaly. Yet, life-style modifications, identification and correction of hypertension must not be lost sight of. Finally stress relieving activities, show-cased by yoga and related techniques could offer additional measures to improve mental and thereby physical health.
|Known hypertension||2073 (23.14%)|
|Known CAD||397 (4.43%)|
|Current smokers (men)||1264 (22.4%)|
|Sedentary men||2986 (89.9%)|
|Sedentary women||2572 (45.6%)|
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