title: Overweight-mortality paradox and impact of six-minute walk distance in lung transplantation.
abstract: Overweight-mortality paradox and impact of six-minute walk distance (SMWD) in lung transplantation.
  
  
  BACKGROUND
  The objective of this study was to examine combined prognostic influence of body mass index (BMI) and SMWD on mortality in lung transplant recipients.
  
  
  METHODS
  Consecutive isolated lung transplant recipients were identified. Preoperative BMI and SMWD data were collected. The cohort was followed for all-cause mortality.
  
  
  RESULTS
  The study included 324 lung transplant recipients with mean age of 57 ± 13 years and 58% were male (27% obstructive, 3% vascular, 6% cystic fibrosis, and 64% with restrictive lung diseases). In the total cohort; 37% had normal BMI, 10% were underweight, 33% were overweight, and 20% were obese. The median SMWD was 700 feet. The lower SMWDgroup was defined as the patients who had SMWD <237 feet as determined by receiver operating characteristic (ROC). Based on this definition, 66 patients (20%) had lower SMWD. There were 71 deaths during a median follow-up of 2.3 years. In multivariate analysis, both BMI and SMWD were independently associated with death. Being overweight was associated with reduced mortality risk (hazard ratio (HR) 0.50, P = 0.042) compared to the normal BMI group, and this was primarily driven by early mortality posttransplant. This paradoxical overweight-mortality relationship remained significant in the lower SMWD group (HR 0.075, P = 0.018), but not in the higher SMWD group (P = 0.552).
  
  
  CONCLUSIONS
  In lung transplant recipients under lung allocation score (LAS) era, pretransplant BMI and SMWD were independent predictors for mortality after the transplant. The lowest mortality risk was noted in a group of transplant recipients identified as overweight; whereas, being underweight or obese was associated with increased mortality.
authors.affiliation: Department of Medicine, Houston Methodist Hospital, Houston, United States.
authors.forename: Kongkiat
authors.initials: K
authors.lastname: Chaikriangkrai
authors.affiliation: Department of Medicine, Houston Methodist Hospital, Houston, United States.
authors.forename: Hye Yeon
authors.initials: HY
authors.lastname: Jhun
authors.affiliation: Department of Pathology and Genomic Medicine, Houston Methodist Research Institute, Houston, Texas, United States.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Graviss
authors.affiliation: Department of Medicine, Houston Methodist Hospital, Houston, United States.
authors.forename: Soma
authors.initials: S
authors.lastname: Jyothula
keywords: Body mass index; body composition; lung transplant; obesity paradox; six-minute walk