title: Extracorporeal membrane oxygenation as a bridge to lung transplantation: what lessons might we learn from volume and expertise?
abstract: OBJECTIVE
  We sought to evaluate the effect of centre volume on survival when extracorporeal membrane oxygenation (ECMO) is used as a bridge to lung transplantation (LTx).
  
  
  METHODS
  We performed a retrospective analysis of the United Network for Organ Sharing data on adult lung transplantations performed between 2000 and 2014. Centres were categorized based on volume of transplants into low-, medium- and high-volume centres (1-5, 6-15 and >15, respectively). Baseline characteristics were assessed and a Kaplan-Meier analysis was used to estimate survival with log-rank test. We used multivariate Cox regression analysis to estimate the risk of post-transplant 1-year mortality between centres.
  
  
  RESULTS
  A total of 342 adult recipients were bridged on ECMO. Of these recipients, 88 (25.7%) were bridged in low, 89 (26%) in medium and 165 (48.2%) in high-volume centres. Patients in medium-volume centres were more likely to be older compared with those in low-volume and high-volume centres with a median age of 56, 46 and 49 years, respectively. High-volume centres reported the highest proportion (94.6%) of bilateral lung recipients, followed by low-volume (86.4%) and medium-volume centres (77.5%). The 30-day survival for the three groups was similar but 1-year survival was higher in high-volume centres (80.8) compared with medium-volume centres (70.0%) and low-volume centres (61.9%). The risk of 1-year mortality in low-volume centres was higher compared with high-volume centres in adjusted analysis (hazard ratio 2.74, 95% confidence interval 1.61-4.68, P = 0.01).
  
  
  CONCLUSIONS
  Lowest volume centres have lowest survival and there exists a volume threshold at which better outcomes are achieved.
authors.affiliation: Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA jhayanga@me.com.
authors.forename: Jeremiah W Awori
authors.initials: JW
authors.lastname: Hayanga
authors.affiliation: Department of Surgical Critical Care, MedStar Washington Hospital Center, Washington, DC, USA.
authors.forename: Alena
authors.initials: A
authors.lastname: Lira
authors.affiliation: Department of Surgery, Hospital of University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Aboagye
authors.affiliation: Department of Cardiac Anesthesia, Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: Heather K
authors.initials: HK
authors.lastname: Hayanga
authors.affiliation: Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: D'Cunha
mesh_terms: D000328:Adult; D016208:Databases, Factual; D015199:Extracorporeal Membrane Oxygenation / Q000009:adverse effects / Q000401:mortality; D005260:Female; D061847:Hospitals, High-Volume; D061846:Hospitals, Low-Volume; D006801:Humans; D053208:Kaplan-Meier Estimate; D008171:Lung Diseases / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D016040:Lung Transplantation / Q000009:adverse effects / Q000401:mortality; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D009927:Tissue and Organ Procurement; D016896:Treatment Outcome; D014481:United States
keywords: Extracorporeal membrane oxygenation; Lung transplantation; Volume