Association of body mass index and long-term outcomes in older patients with non-ST-segment-elevation myocardial infarction: results from the CRUSADE Registry

Abstract

Background: Prior studies have found that obese patients have paradoxically lower in-hospital mortality after non-ST-segment-elevation myocardial infarction than their normal-weight counterparts, yet whether these associations persist long term is unknown.

Methods and results: We linked detailed clinical data for patients with non-ST-segment-elevation myocardial infarction aged ≥65 years in the Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the American College of Cardiology/American Heart Association Guidelines (CRUSADE) Registry to Medicare claims data to obtain longitudinal outcomes. Using height and weight measured on admission, patients were categorized into 6 body mass index (BMI [kilograms per meter squared]) groups. Multivariable Cox proportional hazards models were used to estimate the association between BMI and (1) all-cause mortality, (2) all-cause readmission, (3) cardiovascular readmission, and (4) noncardiovascular readmission for 3 years after hospital discharge. Among older patients with non-ST-segment-elevation myocardial infarction (n=34,465), 36.3% were overweight and 27.7% were obese. Obese patients were younger and more likely to have hypertension, diabetes mellitus, and dyslipidemia than normal or underweight patients. Relative to normal-weight patients, long-term mortality was lower for patients classified as overweight (BMI, 25.0-29.9), obese class I (BMI, 30.0-34.9), and obese class II (BMI, 35.0-39.9), but not obese class III (BMI ≥40.0). In contrast, 3-year all-cause and cardiovascular readmission were similar across BMI categories. Relative to normal-weight patients, noncardiovascular readmissions were similar for obese class I but higher for obese class II and obese class III.

Conclusions: All-cause long-term mortality was generally lower for overweight and obese older patients after non-ST-segment-elevation myocardial infarction relative to those with normal weight. Longitudinal readmissions were similar or higher with increasing BMI.

Keywords: acute coronary syndrome; obesity.