QJM Advance Access originally published online on January 19, 2008
QJM 2008 101(3):231-236; doi:10.1093/qjmed/hcm151
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Ethnic differences in myocardial infarction in patients with hypertension: effects of diabetes mellitus
From the 1Healthy Hearts Institute and the University Department of Medicine, Sandwell and West Birmingham Hospitals NHS Trust, and 2Cardiovascular Research Group, Division of Cardiovascular and Endocrine Sciences, University of Manchester, UK
Address correspondence to Dr J. V. Patel, Sandwell General Hospital, West Bromwich, B71 4HJ, UK. email: Jeetesh.Patel{at}swbh.nhs.uk
Received 20 August 2007 and in revised form 12 November 2007
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Abstract |
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Background: It has been reported that hypertension carries a greater risk of myocardial infarction (MI) in South Asians living in the UK than in the indigenous British population. This has been attributed to some specifically Asian susceptibility factor.
Design: Using a longitudinal approach, we investigated the relationship between coronary heart disease (CHD) risk factors amongst hypertension patients attending Sandwell and City Hospitals, and the onset of cardiovascular events over a 5-year follow-up period.
Results: A total of 350 Caucasian (83.7% male) and 104 South Asian (66.3% male) patients with hypertension [age 63.7 (7.6) years and 57.1 (11.1) years respectively, P < 0.001] were followed-up for a mean (SD) period of 64.7(12.1) months. There were 11 (6.4/1000 patient years) cases of MI in Caucasian patients vs. 11 (17.8/1000 patient years) in South Asians, with event-free survival times being significantly lower amongst South Asians (log-rank test P = 0.04). The prevalence of diabetes mellitus was 22.9% higher amongst South Asians (P < 0.001), whilst mean serum cholesterol and fasting triglyceride levels were higher amongst Caucasians (P = 0.001). There were no ethnic differences in HDL cholesterol concentrations, the use of tobacco, statin therapy or anti-platelet therapies (all P = NS), or in composite endpoint (MI, angina, peripheral vascular disease, stroke, revascularization or death; P = 0.74). On Cox regression analysis of all independent cardiovascular risk variables, associated treatments and ethnicity, MI risk was associated with diabetes mellitus (odds ratio 3.77, 95%CI 1.55–9.15, P = 0.003) but not ethnicity per se (P = 0.26).
Conclusion: Increased risk of MI in hypertensive South Asians in the United Kingdom appears to be the result of a higher prevalence of diabetes mellitus. Further work is required to understand the pathophysiological basis with which diabetes increases CHD risk in this ethnic group.