Morbid Obesity is Associated with Significantly Higher Risk of Death After Lung Transplant in Recipients Bridged on Extra-Corporeal Support

Abstract

<h3>Purpose</h3> Critically ill patients requiring mechanical ventilation (MV) and extra-corporeal support (ECMO) require an abundance of resources and have a high risk of death after lung transplant. To help guide selection, we studied the effect of obesity on mortality in this cohort. <h3>Methods</h3> The United Network for Organ Sharing database (1987-2021) was queried to identify adult lung transplant recipients (n=41,920) bridged on MV (n=2,186, 5.2%) and/or ECMO (n=1,307, 3.1%). Among body mass index (BMI) categories, overall survival (OS) was analyzed using Kaplan-Meier estimation and compared using log-rank tests. Cox regression analyses were used to identify risk factors for death. <h3>Results</h3> Obese (BMI Class I: 30-34.9) and morbidly obese (BMI Class II/III: >35) cohorts were identified. In the MV group, 316 (14.5%) had class I and 62 (2.8%) had class II/III obesity. In the ECMO group, 228 (17.4%) had class I and 37 (2.8%) had class II/III obesity. Median lung allocation scores were 87.0 [IQR 67.5-90.5] in the MV group and 89.2 [IQR 86.6-90.8] in the ECMO group. In the MV group, 30 day, 1, 3 and 5-year OS were 89%, 72%, 53% and 40% in class I patients and decreased to 87%, 56%, 37% and 35% in class II/III patients. In the ECMO group, 30 day, 1, 3 and 5-year OS were 93%, 78%, 58% and 44% in class I patients and decreased to 81%, 43%, 28% and 23% in class II/III patients (Figure 1). Risk factors for death included: class I obesity (HR=1.13, p=0.00), class II/III obesity (HR=1.27, p=0.01), BMI<18.5 (HR 1.16, p=0.00), bridging on MV (HR=1.18, p=0.00), pulmonary hypertension (HR=1.17, p=0.032), diabetes (HR=1.15, p=0.013), history of dialysis (HR=2.05, p=0.00), creatinine (HR=1.11, p=0.00), and donor diabetes (HR=1.13, p=0.00). <h3>Conclusion</h3> Morbidly obese (BMI>35) lung transplant recipients bridged on MV and ECMO carry an extremely high risk of death after transplant. These findings likely reflect non-modifiable challenges in perioperative care and should be considered during evaluation for listing.