ArticlesRisk factors for acute myocardial infarction in Indians: a case-control study
Introduction
Individuals of south Asian descent (India, Pakistan, and Bangladesh) have an increased risk of ischaemic heart disease (IHD) compared with most other ethnic groups. The reason for this increased risk, which has been recorded both among south Asian migrants to other countries1, 2 and among Indians in urban India,3, 4 is unclear. Prevalence of conventional risk factors such as smoking, hypertension, and hypercholesterolaemia is no higher in south Asians than in other ethnic groups.1, 5, 6, 7, 8 High triglyceride concentrations, low concentrations of high-density-lipoprotein (HDL) cholesterol, increased visceral fat, and insulin resistance are more prevalent among south Asians, and these factors have been proposed as reasons for the higher risk of IHD.1, 2, 6, 7, 9 However, a variable that is more common among south Asians may not necessarily be associated with IHD risk. Conversely, a factor that is not more common among south Asians may still have an important relation with IHD. Further, since most studies have been based on migrants to western countries, the findings may not necessarily apply to the vast majority of South Asians who live in their own countries. Therefore, we conducted a hospital-based case-control study of patients with a first myocardial infarction in Bangalore, India, to assess the relative importance of the risk factors for IHD among south Asians.
Section snippets
Cases
200 consecutive patients aged 30-60 years (inclusive) admitted to the coronary care unit of St John's Medical College Hospital with an acute myocardial infarction (AMI) were prospectively recruited as cases. AMI was defined as typical chest pain lasting at least 20 min and an electrocardiogram (ECG) showing ST elevation of at least 2 mm in two or more contiguous leads with subsequent evolution of the ECG and diagnostic enzyme changes (doubling of creatine kinase with at least 10% MB fraction).
Results
The demographic characteristics and lipid data of the 200 cases and 200 controls are shown in table 1. Cases had significantly lower monthly incomes than controls, and significantly fewer of them had a college education. The odds ratio (OR) for AMI was 0·32 (95% CI 0·16-0·66) for the highest versus lowest income group and 0·75 (0·48-1·17) for the middle versus lowest income groups.
Discussion
Our study, which is probably the first prospective case-control study aimed at identifying the relation between risk factors and AMI in south Asians in India, shows that tobacco smoking, a history of hypertension, a high prevalence of diabetes, increased fasting blood glucose (even in those who are not diabetic), and an increased ratio of visceral to total body fat (WHR) are independent risk factors for AMI. Patients with multiple risk factors have a substantially increased risk for AMI.
Our
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