Marital Status, Education, and Risk of Acute Myocardial Infarction in Mainland China: The INTER-HEART Study

BACKGROUND We investigated the effects of marital status and education on the risk of acute myocardial infarction (AMI) in a large-scale case-control study in China. METHODS This study was part of the INTER-HEART China case-control study. The main outcome measure was first AMI. Incident cases of AMI and control patients with no past history of heart disease were recruited. Controls were matching by age (±5 years) and sex. Marital status was combined into 2 categories: single and not single. Education level was classified into 2 categories: 8 years or less and more than 8 years. RESULTS From 1999 to 2002, we recruited 2909 cases and 2947 controls from 17 cities. After adjustment for age, sex, BMI, psychosocial factors, lifestyle, other factors, and mutually for other risk factors, the odds ratio (OR) for AMI associated with being single was 1.51 (95% confidence interval: 1.18-1.93) overall, 1.19 (0.84-1.68; P = 0.072) in men and 2.00 (1.39-2.86; P < 0.0001) in women. The interaction of sex and marital status was statistically significant (P = 0.045). Compared with a high education level, a low education level increased the risk of AMI (1.45, 1.26-1.67); the odds ratios in men and women were 1.29 (1.09-1.52) and 1.55 (1.16-2.08), respectively. Single women with a low education level had a high risk of AMI (2.95, 1.99-4.37). CONCLUSIONS Being single was consistently associated with an increased risk for AMI, particularly in women. In addition, as compared with high education level, low education level was associated with a higher risk of AMI in both men and women.