Key result
Elevated BMI was associated with reduced inpatient mortality following AMI compared to non-obese patients (e.g., Class 1-2 obesity aOR 0.586; 95% CI 0.560-0.612; P<0.001).
Why the study?
Obesity is an established cardiovascular risk factor, but its impact on acute myocardial infarction outcomes remains uncertain given previous literature suggesting an obesity paradox.
Does elevated BMI reduce inpatient mortality in patients hospitalized with acute myocardial infarction?
Cross-Sectional (n=4,401,779)
Yes
Does elevated BMI reduce inpatient mortality in patients hospitalized with acute myocardial infarction?
Odds Ratio: 0.586 (95% CI 0.56–0.612)
p-value: p=<0.001
Elevated BMI is associated with lower inpatient mortality and higher routine discharge following AMI, supporting the existence of an obesity paradox, though the survival benefit is attenuated in Class 3 obesity.
Elevated BMI linked to lower AMI mortality; supports obesity paradox in observational data but leaves causal and management questions open.
Background /Research Question: Obesity is an established cardiovascular disease risk factor, yet its impact on acute myocardial infarction (AMI) outcomes remains uncertain. Previous literature has identified a survival advantage in patients with elevated body mass indices (BMI), a phenomenon termed the "obesity paradox." This study aimed to evaluate the association between elevated BMI and clinical outcomes following AMI. Study Design and Methods A retrospective cross-sectional analysis was conducted using data from the National Inpatient Sample (2015-2022). This nationally representative sample included patients ≥18 years-old in the United States hospitalized with AMI. Patients were stratified into four groups: non-obese, overweight, obesity Class 1-2, and obesity Class 3. Outcomes included inpatient mortality, routine discharge, complications, comorbidities and receipt of revascularization procedures. Propensity score-based inverse probability of treatment weighting (IPTW) adjusted for confounding factors. Multivariable logistic regression evaluated adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for all outcomes. Results Among 4,401,779 AMI hospitalizations, 3,431,939 (78.0%) were non-obese, 98,790 (2.2%) overweight, 647,900 (14.7%) Class 1-2 obese, and 223,150 (5.1%) Class 3 obese. Following IPTW adjustment, all obesity levels demonstrated reduced inpatient mortality compared to non-obese patients (Overweight – aOR 0.541, 95% CI [0.495-0.591], p<0.001; Class 1-2 – 0.586 [0.560-0.612], p<0.001; Class 3 – 0.696 [0.655-0.740], p<0.001). Similarly, the likelihood of routine discharge was significantly higher in all levels besides Class 3 Obesity (Overweight – 1.12 [1.08-1.17], p<0.001; Class 1-2 – 1.14 [1.12-1.16], p<0.001; Class 3 – 0.984 [0.954-1.01], p=0.302). Each obesity level exhibited a mixed complication and comorbidity profile compared to non-obese patients, demonstrating similar nonlinear associations consistently. Interpretation Elevated BMI was associated with lower inpatient mortality and higher routine discharge, although these associations varied across obesity severity. The association with reduced inpatient mortality was attenuated in Class 3 obesity. These findings are consistent with the obesity paradox and highlight the complex relationship between adiposity and short-term outcomes following AMI.
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Malhotra et al. (2026) conducted a cross-sectional in acute myocardial infarction (n=4,401,779). Elevated BMI vs. Non-obese was evaluated on inpatient mortality (aOR 0.586, 95% CI 0.560-0.612, p=<0.001). Elevated BMI was associated with reduced inpatient mortality following AMI compared to non-obese patients (e.g., Class 1-2 obesity aOR 0.586; 95% CI 0.560-0.612; P<0.001).
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