Weight Change and Outcomes in Lung Transplant Recipients

Abstract

Purpose Lung transplantation is a lifesaving therapy in patients with advanced lung disease. A body mass index (BMI) >30 is associated with worse outcomes after lung transplantation. Therefore, a BMI above 30 is considered a relative contraindication for lung transplantation. However, it is not clear how weight change after lung transplantation affects outcomes. We investigated the impact of weight change after lung transplantation on outcomes. Methods We retrospectively assessed BMI and several post-transplant outcomes in 78 consecutive lung transplant recipients. The data was analyzed using R 4.0.2 (The R Foundation for Statistical Computing http://www.R-project.org). Packages Performance Analytics and ggplot2 were used in addition to core R. FVC was modeled as a linear regression against BMI at transplant. To show a different approach, FEV1 was modeled by group of BMI, breaking the BMI values in three equal sets. We checked our hypothesis that people with lower BMI had better lung function when their weight increased from consult to one year after transplant by running a Wilcoxon Sum-Rank test. Results We evaluated 78 lung transplant recipients, 39 of whom were female. The average age was 55 years. The average transplant BMI was 24.3 with a range from 16.8 to 32.2. At one year post transplant, the average BMI was 25.7. By BMI, 33% of recipients were overweight at the time of transplant and 5% were obese. Higher BMI was associated with increased length of stay (LOS) and decreased FVC and FEV1 at 1 year post transplant compared to those with normal BMIs. More than half the patients who needed to lose weight for transplant re-gained the weight by 1 year post transplant. Underweight recipients who gained weight after transplant had increased FVC and FEV1 compared to those who didn't gain weight. Conclusion A rather large proportion of lung transplant candidates are overweight by BMI criteria. A higher BMI was associated with a longer LOS after transplant. One year pulmonary function (PFT) data was also worse in patients with higher BMIs compared to those with normal BMIs. Interestingly, underweight patients who gained weight after lung transplant had a strong trend for statistically significant improvement in PFT one year after lung transplant. Larger studies are needed to better understand the impact of weight change on outcomes after lung transplant.