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A Global Case-Control Study of Risk Factors for Acute Myocardial Infarction
Dr. S. Yusuf (Principal Investigator) Background: Although cardiovascular disease mortality has declined in most developed countries, increases are occurring in developing countries. Our knowledge of risk factors for acute myocardial infarction is largely derived from studies in the developed countries. Applicability of these results to other populations is unknown. Therefore we are conducting INTER-HEART, a case-control study in >50 countries, to determine the association between risk factors and acute myocardial infarction within populations defined by ethnicity and/or geographic region, and to assess the relative importance of risk factors across these populations Hypothesis: We hypothesize that the relative impact of conventional risk factors (smoking, hypertension, elevated cholesterol, diabetes) and emerging risk factors (glucose abnormalities, abdominal obesity, homocysteine, other nutritional, psychosocial) for cardiovascular disease differs between people of varying ethnic and geographic origin. Methods: INTER-HEART is a study of approximately 14,000 incident cases of acute myocardial infarction and 16,000 controls matched by age (+/- 5 years) and sex, with no history of heart disease. Recruitment will take place in 260 centres from 55 countries in Asia, Europe, Middle Ease Crescent, Africa, Australia, and North and South America. All patients admitted to the coronary care unit or equivalent cardiology ward of participating centres are screened to identify incident cases of acute myocardial infarction. Cases are identified with standardised definitions and enrolled within 24 hours of symptom onset. At least one control per case is recruited with specific criteria. The study questionnaire was translated into 11 languages and collects data on demographic factors (country of origin, first language), socioeconomic status (education, occupation, income), lifestyle (tobacco use, physical activity, dietary patterns), and personal and family history of cardiovascular disease and risk factors. Trained staff administer the questionnaire before the patient leaves the hospital. The components of the questionnaire were compiled with previously validated questions included in studies of risk factors for cardiovascular disease. Data on medications (prehospital, inhospital, and discharge) and interventions are abstracted from charts. Standard physical measurements are done in duplicate by the same examiner on each participant: height, weight, waist, and hip circumference, and heart rate. 20 mL non-fasting blood is drawn to be stored frozen for biochemical analyses (total cholesterol, high-density lipoprotein; apolipoprotein B, immunoglobulin G and immunoglobulin A antibodies indicating infection with Chlamydia pneumoniae , glycated haemoglobin, homocysteine, serum folate, serum albumin, serum creatinine, white cell count). Genetic materials (buffy coat) will also be collected to assess the relevance of candidate genes for acute myocardial infarction within each ethnic group. Conditional logistic regression will be employed to assess a) the relationship between AMI and risk factors within countries or regions, and b) the relationship between risk factors and disease across countries or regions. Overall effect estimates will be derived from the region-specific estimates using mixed effects model. Sponsor: INTER-HEART is sponsored by the World Health Organization, the World Heart Federation, and has received funding from >40 visible funding sources, including peer-review agencies and industry. Start Date: A vanguard phase (February 1999-2000) enrolled 4,000 subjects from 41 countries. Full data collection will take place between April, 2000 and October, 2002. As of June, 2002, data has been collected from >22,000 patients.
Finish Date:
December 2002 |