Sex-specific associations between body mass index and short-term outcomes in patients with acute myocardial infarction

Abstract

Body mass index (BMI) has been associated with prognosis in patients with acute myocardial infarction (AMI), yet potential sex-specific differences remain insufficiently characterized. We aimed to evaluate sex-specific associations between BMI and short-term mortality in AMI patients. This multicenter, real-world cohort study enrolled consecutive AMI patients from 82 hospitals between 2010 and 2024, including 67,183 men and 34,110 women. BMI was categorized according to Chinese criteria as underweight (<18.5 kg/m²), normal weight (18.5–23.9 kg/m²), overweight (24.0–27.9 kg/m²), and obese (≥28.0 kg/m²). Baseline characteristics, comorbidities, in-hospital treatments, and outcomes were compared across BMI categories stratified by sex. Sex-stratified multivariable Cox proportional hazards models were used to estimate 3-month all-cause mortality. Patients in the Underweight group were notably older. Obese patients had the highest prevalence of cardiovascular risk factors, including Diabetes Mellitus (Male: 17.7% vs. 24.7% vs. 28.6% vs. 31.1%, p<0.001; Female: 16.4% vs. 29.6% vs. 35.4% vs. 37.1%, p<0.001) and Hypertension (Male: 42.5% vs. 45.3% vs. 49.3% vs. 52.6%, p<0.001; Female: 39.6% vs. 51.1% vs. 56.0% vs. 59.4%, p<0.001). Regarding in-hospital management, Obese patients more frequently received revascularization (Male: 46.2% vs. 60.7% vs. 63.7% vs. 65.0%, p<0.001; Female: 29.6% vs. 44.9% vs. 50.1% vs. 50.1%, p<0.001) and guideline-directed medical therapy (Figure 1). After multivariable adjustment, obesity was independently associated with increased 3-month mortality in men (aHR: 1.13, 95% CI: 1.01–1.26; p = 0.039), whereas overweight and underweight were not significantly associated with mortality. In women, overweight was associated with reduced 3-month mortality (aHR: 0.89, 95% CI: 0.81–0.97; p = 0.009), while obesity showed no significant association (p for interaction=0.004) (Figure 2). The prognostic impact of BMI in AMI differs significantly by sex. Obesity confers increased short-term mortality risk in men, whereas overweight is associated with improved survival in women. These findings underscore the importance of incorporating sex–BMI interaction into risk stratification strategies for AMI patients.Baseline Characteristics TableGender-stratified BMI & 3-month mortality