Articles Introduction Obesity increases the risk of cardiovascular diseases and diabetes, 1,2 but these data are derived mainly from high- income countries. Although most of the global burden of cardiovascular disease is in developing countries, few data are available for the effect of obesity in these populations. 3 Further, we do not know the measure of obesity (body-mass index [BMI], waist or hip circumferences, or waist-to-hip ratio) that shows the strongest relation to the risk of such disease and whether these measures are similar across different ethnic groups, in men and women, and at different ages. 4 Previous studies provided conflicting results, possibly because of the modest number of cardiovascular events (a few hundred). 5–9 On the basis of two previous smaller studies, 10,11 we had postulated that markers of central obesity (especially the waist-to-hip ratio) would be more strongly related to the risk of myocardial infarction than BMI (the conventional measure). We aimed to investigate the relation of BMI, waist and hip circumferences, and waist-to-hip ratio to the risk of myocardial infarction using data from the INTERHEART study, 12,13 of about 15 000 cases and a similar number of controls representing many ethnic groups. Methods Participants We did a standardised case-control study of 15 152 cases of first myocardial infarction, and 14 820 age-matched and sex-matched controls. Details have been published previously. 5 Consecutive cases of first myocardial infarction presenting within 24 h of symptom onset were eligible. All consenting cases without cardiogenic shock or history of major chronic diseases were included. At least one age-matched (5 years) and sex-matched control (without a history of cardiovascular disease) was recruited per case by use of specific criteria. 5 The first control per case was an attendant or relative of a patient from a non-cardiac ward or an unrelated (not first-degree relative) attendant of another cardiac patient. A second control per case was selected from those at the same centre with illnesses not obviously related to coronary heart disease or its risk factors. Lancet 2005; 366: 1640–49 See Comment page 1589 *See Lancet Online for webappendix and a full list of investigators Population Health Research Institute, McMaster University and Hamilton Health Sciences, Hamilton, Canada (Prof S Yusuf DPhil, S Hawken MSc, S Ôunpuu PhD, Prof A M Sharma MD, S Anand MD, F Razak MSc); University of Wisconsin Medical School, Wisconsin, USA (L Bautista MD); Istituto Mario Negri, Milano, Italy (M Grazia Franzosi PhD); University of Cape Town, South Africa (Prof P Commerford MBChB); Ninewells Hospital and Medical School, Dundee, UK (Prof C C Lang MD); University of Split, Croatia (Z Rumboldt MD); Gaborone Private Hospital, Botswana (C Onen FRCP); Cardiovascular Institute and Fu Wai Hospital, Beijing, China (Prof L Lisheng MD); Ramathibodi Hospital, Bangkok, Thailand (S Tanomsup MD); and Nairobi Women’s Hospital, Nairobi, Kenya (P Wangai Jr MD) Correspondence to: Dr Salim Yusuf, Population Health Research Institute, Hamilton General Hospital, Hamilton, Ontario L8L 2X2, Canada yusufs@mcmaster.ca 1640 www.thelancet.com Vol 366 November 5, 2005 Obesity and the risk of myocardial infarction in 27 000 participants from 52 countries: a case-control study Salim Yusuf, Steven Hawken, Stephanie Ôunpuu, Leonelo Bautista, Maria Grazia Franzosi, Patrick Commerford, Chim C Lang, Zvonko Rumboldt, Churchill L Onen, Liu Lisheng, Supachai Tanomsup, Paul Wangai Jr, Fahad Razak, Arya M Sharma, Sonia S Anand, on behalf of the INTERHEART Study Investigators* Summary Background Obesity is a major risk factor for cardiovascular disease, but the most predictive measure for different ethnic populations is not clear. We aimed to assess whether markers of obesity, especially waist-to-hip ratio, would be stronger indicators of myocardial infarction than body-mass index (BMI), the conventional measure. Methods We did a standardised case-control study of acute myocardial infarction with 27 098 participants in 52 countries (12 461 cases and 14 637 controls) representing several major ethnic groups. We assessed the relation between BMI, waist and hip circumferences, and waist-to-hip ratio to myocardial infarction overall and for each group. Findings BMI showed a modest and graded association with myocardial infarction (OR 1·44, 95% CI 1·32–1·57 top quintile vs bottom quintile before adjustment), which was substantially reduced after adjustment for waist-to-hip ratio (1·12, 1·03–1·22), and non-significant after adjustment for other risk factors (0·98, 0·88–1·09). For waist-to- hip ratio, the odds ratios for every successive quintile were significantly greater than that of the previous one (2nd quintile: 1·15, 1·05–1·26; 3rd quintile: 1·39; 1·28–1·52; 4th quintile: 1·90, 1·74–2·07; and 5th quintiles: 2·52, 2·31–2·74 [adjusted for age, sex, region, and smoking]). Waist (adjusted OR 1·77; 1·59–1·97) and hip (0·73; 0·66–0·80) circumferences were both highly significant after adjustment for BMI (p0·0001 top vs bottom quintiles). Waist-to-hip ratio and waist and hip circumferences were closely (p0·0001) associated with risk of myocardial infarction even after adjustment for other risk factors (ORs for top quintile vs lowest quintiles were 1·75, 1·33, and 0·76, respectively). The population-attributable risks of myocardial infarction for increased waist-to-hip ratio in the top two quintiles was 24·3% (95% CI 22·5–26·2) compared with only 7·7% (6·0–10·0) for the top two quintiles of BMI. Interpretation Waist-to-hip ratio shows a graded and highly significant association with myocardial infarction risk worldwide. Redefinition of obesity based on waist-to-hip ratio instead of BMI increases the estimate of myocardial infarction attributable to obesity in most ethnic groups.