Influence of socioeconomic status on acute myocardial infarction in the Chinese population: the INTERHEART China study.

BACKGROUND Many researches report that low socioeconomic status (SES) is associated with a higher risk of coronary heart disease (CHD). This study aimed to determine whether levels of education, family income, and other SES were associated with acute myocardial infarction (AMI) in the Chinese population, and to compare the difference in this association between northern and southern regions in China. METHODS We conducted a case-control study. Cases were first AMI (n = 2909). Controls (n = 2947) were randomly selected and frequency matched to cases on age and sex. SES was measured using education, family income, possessions in the household, and occupation. RESULTS Low levels of education (8 years) were more common in cases compared to controls (53.4% and 44.1%; P = 0.0001). After adjusting all risk factors, the level of education was associated with AMI risk in the Chinese population (P = 0.0005). The odds ratio (OR) associated with education of 8 years or less, compared with more than 12 years (trade school/college/university) was 1.33 (95%CI 1.12 - 1.59), and for education of 9 - 12 years 1.04 (95%CI 0.88 - 1.33). The proportion of higher income population was more in controls than cases (39.4% and 35.3%). Number of possessions and non-professional occupation were only weakly or not at all independently related to AMI. The adjusted OR associated with the lower education was 2.38 (95%CI 1.67 - 3.39) in women, and 1.18 (95%CI 0.99 - 1.42) in men (P = 0.0001, for heterogeneity). The interaction between levels of education and different regions was significant (P = 0.0206, for interaction). CONCLUSION Several socioeconomic factors including levels of education and income were closely associated with increase of AMI risk in China, most markedly in northeast and southern area. The effect of education was stronger towards AMI in women than men.