The Impact of Waiting List BMI Changes on the Short-term Outcomes of Lung Transplantation

Background. Obesity and underweight are associated with a higher postlung transplantation (LTx) mortality. This study aims to assess the impact of the changes in body mass index (BMI) during the waiting period for LTx on early postoperative outcomes. Methods. Medical records of 502 consecutive cases of LTx performed at our institution between 1999 and 2015 were reviewed. Patients were stratified per change in BMI category between pre-LTx assessment (candidate BMI) and transplant BMI as follows: A-candidate BMI, less than 18.5 or 18.5 to 29.9 and transplant BMI, less than 18.5; B-candidate BMI, less than 18.5 and transplant BMI, 18.5 to 29.9; C-candidate BMI, 18.5 to 29.9 and transplant BMI, 18.5 to 29.9; D-candidate BMI, 30 or greater and transplant BMI, 18.5 to 29.9; and E-candidate BMI, 30 or greater or 18.5 to 29.9 and transplant BMI, 30 or greater. Our primary outcome was in-hospitalmortality and secondary outcomes were length of mechanical ventilation, intensive care unit length of stay (LOS), hospital LOS and postoperative complications. Results. BMI variation during the waiting time was common, as 1/3 of patients experienced a change in BMI category. Length of mechanical ventilation (21 days vs 9 days; P = 0.018), intensive care unit LOS (26 days vs 15 days; P = 0.035), and rates of surgical complications (76% vs 44%; P = 0.018) were significantly worse in patients of group E versus group D. Obese candidates who failed to decrease BMI less than 30 by transplant exhibited an increased risk of postoperative mortality (odds ratio, 2.62; 95% confidence interval, 1.01-6.48) compared with patients in group C. Pre-LTx BMI evolution had no impact on postoperative morbidity and mortality in underweight patients. Conclusions. Our results suggest that obese candidates with an unfavorable pretransplant BMI evolution are at greater risk of worse postLTx outcomes.