Rationale: Many lung transplant recipients with cystic fibrosis (CF) have low preoperative body mass index (BMI); however, post-transplant BMI recovery is not well understood. Objectives: To evaluate BMI recovery (⩾18.5 kg/m2) among CF lung transplant recipients with low preoperative BMI and to investigate the association of survival with BMI recovery. Methods: The United Network for Organ Sharing and CF Foundation patient registries (June 2005-December 2016) were used to identify CF lung transplant recipients. Among recipients surviving ⩾1 year, Cox modeling compared post-transplant 1-year conditional survival between recipients with low (<17 and 17-18.49 kg/m2) versus normal preoperative BMI, stratified by BMI recovery. Results: Of 1,977 CF lung transplant recipients, 272 (14%) and 449 (23%) had a preoperative BMI of <17 and 17-18.49 kg/m2, respectively. For subgroups with a BMI of <17 and 17-18.49 kg/m2, 29% versus 49%, respectively, of those alive at 1 year recovered their BMI. Among recipients with low preoperative BMI, adjusted post-transplant 1-year conditional survival was worse than that in those with preoperative BMI ⩾ 18.5 kg/m2; however, BMI recovery mitigated this. Preoperative BMI < 17 kg/m2 had an adjusted hazard ratio of 1.29 (95% confidence interval [CI], 0.92-1.81) with BMI recovery versus 1.57 (95% CI, 1.09-2.25) without recovery, and preoperative BMI 17-18.49 kg/m2 had an adjusted hazard ratio of 1.28 (95% CI, 1.02-1.61) with BMI recovery versus 1.72 (95% CI, 1.14-2.59) without recovery. Conclusions: Patients with lower preoperative BMI were less likely to achieve BMI recovery within 1 year. However, for those who did, BMI recovery within 1 year after transplant was associated with longer survival.
Keywords: BMI; forced expiratory volume in 1 second; lung function; survival; underweight.