Objective: To determine the effect of education and other measures of socioeconomic status (SES) on risk of acute myocardial infarction (AMI) in patients and controls from countries with diverse economic circumstances (high, middle, and low income countries).
Design: Case-control study.
Setting: 52 countries from all inhabited regions of the world.
Participants: 12242 cases and 14622 controls.
Main outcome measures: First non-fatal AMI.
Results: SES was measured using education, family income, possessions in the household and occupation. Low levels of education (⩽8 years) were more common in cases compared to controls (45.0% and 38.1%; p<0.0001). The odds ratio (OR) for low education adjusted for age, sex and region was 1.56 (95% confidence interval 1.47 to 1.66). After further adjustment for psychosocial, lifestyle, other factors and mutually for other socioeconomic factors, the OR associated with education ⩽8 years was 1.31 (1.20 to 1.44) (p<0.0001). Modifiable lifestyle factors (smoking, exercise, consumption of vegetables and fruits, alcohol and abdominal obesity) explained about half of the socioeconomic gradient. Family income, numbers of possessions and non-professional occupation were only weakly or not at all independently related to AMI. In high-income countries (World Bank Classification), the risk factor adjusted OR associated with low education was 1.61 (1.33 to 1.94), whereas it was substantially lower in low-income and middle-income countries: 1.25 (1.14 to 1.37) (p for interaction 0.045).
Conclusion: Of the SES measures we studied, low education was the marker most consistently associated with increased risk for AMI globally, most markedly in high-income countries.
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▸ Additional tables are published online only at http://heart.bmj.com/content/vol95/issue24
Funding SY was supported by a senior scientist award of the CIHR and holds an endowed chair of the Heart and Stroke Foundation of Ontario. CKC is supported through a Cottrell scholarship, Royal Australasian College of Physicians and a Public Health (Sidney Sax) Overseas Fellowship cofunded by NHMRC and NHF of Australia. SVS is supported by the National Institutes of Health Career Development Award (NHLBI 1 K25 HL081275). The INTERHEART study was funded by the Canadian Institute of Health Research, the Heart and Stroke Foundation of Ontario, the International Clinical Epidemiology Network (INCLEN) and through unrestricted grants from several pharmaceutical companies, with major contributions from AstraZeneca, Novartis, Hoechst Marion Roussel (now Aventis), Knoll Pharmaceuticals (now Abbott), Bristol Myers Squibb, King Pharma and Sanofi-Sythelabo, and by various national bodies in different countries: Chile: Universidad de la Frontera, Sociedad Chilena de Cardiologia Filial Sur; Colombia: Colciencias, Ministerio de Salud; Croatia: Croatian Ministry of Science and Technology; Guatemala: Liga Guatemalteca del Corazon; Hungary: Astra Hassle, National Health Science Council, George Gabor Foundation; Iran: Iran Ministry of Health; Italy: Boehringer-Ingelheim; Japan: Sankyo Pharmaceutical Co, Banyu Pharmaceutical Co, Astra Japan; Kuwait: Endowment Fund for Health Development in Kuwait; Pakistan: ATCO Laboratories; Philippines: Philippine Council For Health Research and Development, Pfizer Philippines Foundation, Astra Pharmaceutical, and the Astra Fund for Clinical Research and Continuing Medical Education, Pharmacia and Upjohn; Poland: Foundation PROCLINICA, State Committee for Scientific Research; Singapore: Singapore National Heart Association; South Africa: MRC South Africa, Warner-Parke-Davis Pharmaceuticals, Aventis; Sweden: Swedish Heart and Lung Foundation, the Swedish Council for Working Life and Social Research; Thailand: The Heart Foundation of Thailand, Thailand Research Fund; USA: King Pharma. Role of the study sponsors or funders: in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication: none. Researchers were independent from funders.
Competing interests None.
Ethics approval The protocol was approved by the ethics committee at each of the participating centres and all participants provided written informed consent.
Provenance and Peer review Not commissioned; not externally peer reviewed.