Pre-Transplant Body Mass Index (BMI) is Associated with Survival after Bilateral Lung Transplantation

Purpose BMI outside of the range 16-30 kg/m2 is considered a relative contraindication to lung transplantation. We hypothesised that patients transplanted outside of this target range would have poorer graft survival compared to recipients within this range. Methods A single center retrospective analysis was performed of all first bilateral lung transplant (BLTx) recipients with available pre-transplant BMI data, between January 2000-October 2018. Graft survival was defined as time to death or re-transplantation. Kaplan-Meier curves were generated for recipients with a pre-transplant BMI > 30, and those with a BMI < 16, and compared to those within the recommended range, using the Log-Rank test and the Gehan-Breslow-Wilcoxon test. Results 671 patients underwent a first BLTx during the study period. 585 patients had a BMI at the time of transplant within the range of 16-30kg/m2. 52 patients had a BMI>30, and 34 had a BMI<16. Between the BMI<16 and BMI 16-30 groups, there were significant differences in patient age (median age 37.5 vs 51, p<0.01) and native lung disease (CF 53% vs 27%, p<0.01). Between the BMI 16-30 and BMI >30 groups there was a significant difference in native lung disease (ILD 21% vs 42%, p<0.01). Median graft survival was 2970 days for BMI 16-30, 2035 days for BMI>30 and 3434 days for BMI<16. Survival was significantly shorter for patients with BMI>30 compared to BMI 16-30 (p=0.04) [figure 1A]. There was no significant difference in survival between patients with BMI<16 and BMI 16-30(p=0.80) [figure 1B]. Conclusion Patients with a pre-transplant BMI>30 had significantly shorter survival than those with target range BMI. Younger patients with BMI < 16 did not demonstrate inferior survival to those with target range BMI. These results require additional validation with multivariate assessment. Our results suggest that BMI > 30 should remain a relative contra-indication to lung transplantation but BMI < 16 in carefully selected younger patients is not. BMI outside of the range 16-30 kg/m2 is considered a relative contraindication to lung transplantation. We hypothesised that patients transplanted outside of this target range would have poorer graft survival compared to recipients within this range. A single center retrospective analysis was performed of all first bilateral lung transplant (BLTx) recipients with available pre-transplant BMI data, between January 2000-October 2018. Graft survival was defined as time to death or re-transplantation. Kaplan-Meier curves were generated for recipients with a pre-transplant BMI > 30, and those with a BMI < 16, and compared to those within the recommended range, using the Log-Rank test and the Gehan-Breslow-Wilcoxon test. 671 patients underwent a first BLTx during the study period. 585 patients had a BMI at the time of transplant within the range of 16-30kg/m2. 52 patients had a BMI>30, and 34 had a BMI<16. Between the BMI<16 and BMI 16-30 groups, there were significant differences in patient age (median age 37.5 vs 51, p<0.01) and native lung disease (CF 53% vs 27%, p<0.01). Between the BMI 16-30 and BMI >30 groups there was a significant difference in native lung disease (ILD 21% vs 42%, p<0.01). Median graft survival was 2970 days for BMI 16-30, 2035 days for BMI>30 and 3434 days for BMI<16. Survival was significantly shorter for patients with BMI>30 compared to BMI 16-30 (p=0.04) [figure 1A]. There was no significant difference in survival between patients with BMI<16 and BMI 16-30(p=0.80) [figure 1B]. Patients with a pre-transplant BMI>30 had significantly shorter survival than those with target range BMI. Younger patients with BMI < 16 did not demonstrate inferior survival to those with target range BMI. These results require additional validation with multivariate assessment. Our results suggest that BMI > 30 should remain a relative contra-indication to lung transplantation but BMI < 16 in carefully selected younger patients is not.