title: The utility of preoperative six-minute-walk distance in lung transplantation.
abstract: BACKGROUND
  The use of 6-minute-walk distance (6MWD) as an indicator of exercise capacity to predict postoperative survival in lung transplantation has not previously been well studied.
  
  
  OBJECTIVE
  To evaluate the association between 6MWD and postoperative survival following lung transplantation.
  
  
  METHODS
  Adult, first time, lung-only transplantations per the United Network for Organ Sharing database from May 2005 to December 2011 were analyzed. Kaplan-Meier methods and Cox proportional hazards modeling were used to determine the association between preoperative 6MWD and post-transplant survival after adjusting for potential confounders. A receiver operating characteristic curve was used to determine the 6MWD value that provided maximal separation in 1-year mortality. A subanalysis was performed to assess the association between 6MWD and post-transplant survival by disease category.
  
  
  RESULTS
  A total of 9,526 patients were included for analysis. The median 6MWD was 787 ft (25th-75th percentiles = 450-1,082 ft). Increasing 6MWD was associated with significantly lower overall hazard of death (P < 0.001). Continuous increase in walk distance through 1,200-1,400 ft conferred an incremental survival advantage. Although 6MWD strongly correlated with survival, the impact of a single dichotomous value to predict outcomes was limited. All disease categories demonstrated significantly longer survival with increasing 6MWD (P ≤ 0.009) except pulmonary vascular disease (P = 0.74); however, the low volume in this category (n = 312; 3.3%) may limit the ability to detect an association.
  
  
  CONCLUSIONS
  6MWD is significantly associated with post-transplant survival and is best incorporated into transplant evaluations on a continuous basis given limited ability of a single, dichotomous value to predict outcomes.
authors.affiliation: 1 Department of Surgery.|2 Division of Cardiovascular and Thoracic Surgery, and.
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Castleberry
authors.affiliation: 1 Department of Surgery.|3 Duke Clinical Research Institute, Durham, North Carolina.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Englum
authors.affiliation: 4 Division of Pulmonary and Critical Care, Duke University Medical Center, Durham, North Carolina.
authors.forename: Laurie D
authors.initials: LD
authors.lastname: Snyder
authors.affiliation: 1 Department of Surgery.|5 Department of Visceral Surgery and Medicine, Inselspital, University of Berne, Berne, Switzerland; and.
authors.forename: Mathias
authors.initials: M
authors.lastname: Worni
authors.affiliation: 6 Department of General Surgery, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Asishana A
authors.initials: AA
authors.lastname: Osho
authors.affiliation: 1 Department of Surgery.|3 Duke Clinical Research Institute, Durham, North Carolina.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Gulack
authors.affiliation: 4 Division of Pulmonary and Critical Care, Duke University Medical Center, Durham, North Carolina.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Palmer
authors.affiliation: 1 Department of Surgery.|2 Division of Cardiovascular and Thoracic Surgery, and.
authors.forename: R Duane
authors.initials: RD
authors.lastname: Davis
authors.affiliation: 1 Department of Surgery.|2 Division of Cardiovascular and Thoracic Surgery, and.
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Hartwig
mesh_terms: D000328:Adult; D005080:Exercise Test; D017079:Exercise Tolerance; D006801:Humans; D053208:Kaplan-Meier Estimate; D016040:Lung Transplantation / Q000401:mortality*; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D012372:ROC Curve; D012189:Retrospective Studies; D055815:Young Adult
keywords: exercise tolerance; lung transplantation; patient outcome assessment