The obesity paradox, extreme obesity, and long-term outcomes in older adults with ST-segment elevation myocardial infarction: results from the NCDR

To investigate the obesity paradox and association of extreme obesity with long-term outcomes among older ST-segment elevation myocardial infarction (STEMI) patients.

Nineteen thousand four hundred and ninety-nine patients ≥65 years with STEMI surviving to hospital discharge in NCDR ACTION Registry-GWTG linked to Centers for Medicare and Medicaid Services outcomes between 2007 and 2012 were stratified by body mass index (BMI) (kg/m²) into normal weight (18.5–24.9), overweight (25–29.9), class I (30–34.9), class II (35–39.9), and class III/extreme obese (≥40) categories. Multivariable-adjusted associations were evaluated between BMI categories and mortality by Cox proportional hazards models, and days alive and out of hospital (DAOH) by generalized estimating equations, within 3 years after discharge. Seventy percent of patients were overweight/obese and 3% extremely obese. Normal weight patients were older and more likely to smoke; while extremely obese patients were younger and more likely to be female and black, with lower socioeconomic status and more comorbidity (P ≤ 0.001). A U-shaped association was observed between BMI categories and mortality: patients with class I obesity were at lowest risk, while normal weight [hazard ratio (HR) 1.30, 95% confidence interval (CI) 1.15–1.47] and extremely obese patients (HR 1.33, 95% CI 1.02–1.74) had higher mortality. Normal weight [odds ratio (OR) 0.79, 95% CI 0.68–0.90] and extremely obese (OR 0.73, 95% CI 0.54–0.99) individuals also had lower odds of DAOH.

Mild obesity is associated with lower long-term risk in older STEMI patients, while normal weight and extreme obesity are associated with worse outcomes. These findings highlight hazards faced by an increasing number of older individuals with normal weight or extreme obesity and cardiovascular disease.