Sex Differences of Risk Factors for Acute Myocardial Infarction in Japanese Patients

Abstract

Acute myocardial infarction (AMI) is prevalent and has serious consequences including re-infarction and death. Although the risk factors for AMI have been extensively studied in Western countries, they are less well documented in Japan. To determine the risk factors for AMI, we performed a case-control study in unselected patients with AMI. Risk factors were assessed in 1,925 consecutive patients with a first AMI (age, 28-103 years old; men, 1,353; women, 572), who were admitted to one of the major institutes in Japan, and in 2,279 age-and sex-matched population-based controls. Hypertension (odds ratio (OR), 4.80; 95% confidence interval (CI), 3.80 to 5.95; p < 0.01), diabetes (OR, 3.44; 95% CI, 2.50 to 4.75; p < 0.01), current smoking (OR, 3.39; 95% CI, 2.78 to 4.18; p < 0.01), family history (OR, 1.84; 95% CI, 1.30 to 2.62; p < 0.01), and hypercholesterolemia (OR, 1.28; 95% CI, 1.00 to 1.62; p < 0.05) were all independent risk factors for AMI. However, obesity (OR, 1.13; 95% CI, 0.92 to 1.50; NS) was not. Hypertension (OR, 4.80; 95% CI, 3.80 to 6.02; p < 0.01), current smoking (OR, 4.00; 95% CI, 3.02 to 5.00; p < 0.01), and diabetes (OR, 2.9; 95% CI, 2.00 to 4.04; p < 0.01) were all independent risk factors for AMI in men. In contrast, only current smoking (OR, 8.22; 95% CI, 3.98 to 18.88; p < 0.01), diabetes (OR, 6.12; 95% CI, 3.78 to 12.02; p < 0.01), and hypertension (OR, 5.04; 95% CI, 2.92 to 7.52; p < 0.01) were independent risk factors for AMI in women. Hypercholesterolemia was an independent risk factor for AMI in men (OR, 1.52; 95% CI, 1.00 to 1.98; p < 0.05), but not in women. Hypertension, diabetes, current smoking, family history and hypercholesterolemia are associated with AMI in Japanese patients, and the importance of the risk factors for AMI differs between men and women. Hypertension, current smoking, diabetes and family history are the most important risk factors in men, whereas current smoking, diabetes, hypertension and family history are the most important risk factors in women. Hypercholesterolemia is an independent risk factor for AMI in men, but not in women. To the best of our knowledge, this is the first clinical study to define the relative importance of risk factors for AMI in Japanese patients.