Center-Level Variations in Maximum Recipient Body Mass Index in Heart Transplantation

Abstract

This study explored center-level variations in maximum recipient body mass index (BMI) and the associated impact of morbid obesity on outcomes of orthotopic heart transplantation (OHT). Using the United Network for Organ Sharing (UNOS) database, we examined adults (≥18 years) who underwent OHT between 2010 and 2018. Centers performing <10 OHTs per year were excluded. Recipients were stratified by BMI: <35, 35-38, 38 to 40, >40 kg/m2. Kaplan-Meier analysis was utilized to model survival and Cox regression analysis was utilized for adjusted analysis of 1-year mortality. A total of 17,821 candidates underwent OHT with 1,330 having a BMI >35kg/m2. Among 84 centers, a mean of 92.06% of recipients per center had a BMI<35 with 5.87%, 1.01%, and 1.06% of recipients having BMIs of 35 to 38, 38 to 40, and >40 at each center, respectively. A total of 5, 54, 17, and 8 centers had maximum recipient BMIs of <35, 35 to 38, 38 to 40, and >40 kg/m2, respectively. Centers performing OHT on recipients with higher BMIs displayed higher overall OHT volume (p = 0.002). Rates of post-transplant dialysis (p <0.001) and stroke (p = 0.008) were higher with increased BMI and length of stay was significantly longer (p <0.001). Following risk-adjustment, BMI 35 to 38 (HR 1.19) was not associated with increased risk of 1-year mortality although BMI 38 to 40 (HR 1.80, p = 0.007) and >40 (HR 2.85, p <0.001) were associated. In conclusion, most centers in the United States have a maximum recipient BMI of 35 to 38 for OHT, which appears justified as the risk of 1-year mortality increases with BMI >38.