Obesity Is Associated with Increased Mortality in Patients Undergoing Venoarterial Extracorporeal Membrane Oxygenation

OBJECTIVES: To determine the relationship between all-cause hospital mortality and morbidity in patients treated with venoarterial extracorporeal membrane oxygenation (ECMO) and to assess whether this relationship is mediated via body mass index (BMI). DESIGN: Using the Extracorporeal Life Support Organization (ELSO) registry, venoarterial ECMO runs from 2015 to 2021 were retrospectively analyzed. Patient demographics, ECMO indications, and complications for survivors and decedents were univariately compared. Logistic regression with fractional polynomials was used to estimate the relationship between BMI and both mortality and complications in venoarterial ECMO patients. SETTING: Contributing centers to the ELSO ECMO registry. PATIENTS: Patients that underwent venoarterial ECMO at an ELSO contributing ECMO center. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Twenty-two thousand eight hundred twenty-five venoarterial ECMO runs met inclusion criteria for analysis. The mean BMI for survivors was 28.4 ± 6.5 vs. 29.5 ± 6.9 kg/m2 for decedents. BMI was significantly associated with mortality (p < 0.001), with the proportion of patients dying increasing with increasing BMI: 47% of underweight patients died, increasing to 50% for the normal range, to 53%, 56%, 58%, and 65% for preobese, class 1, class 2, and class 3 obese patients, respectively. Relative to a BMI of 25, a BMI of 35 had an odds ratio (OR) of death of 1.15 (1.09-1.18), and a BMI of 45 an OR of 1.46 (1.25-1.57). BMI was significantly associated with increased mechanical and renal complications, but decreased pulmonary complications. CONCLUSIONS: In patients undergoing venoarterial ECMO, increasing BMI was associated with increasing all-cause mortality and mechanical and renal complications.