title: Impact of the hepatopulmonary syndrome MELD exception policy on outcomes of patients after liver transplantation: an analysis of the UNOS database.
abstract: OBJECTIVE
  Patients with hepatopulmonary syndrome (HPS) are prioritized for liver transplantation (given exception points) due to their high pre- and post-transplantation mortality. However, few studies have evaluated the outcomes of these patients.
  
  
  METHODS
  We performed a retrospective cohort study using data submitted to the United Network for Organ Sharing in a study of the effects of room-air oxygenation on pre- and post-transplantation outcomes of patients with HPS. We identified thresholds associated with post-transplantation survival using cubic spline analysis and compared overall survival times of patients with and without HPS.
  
  
  RESULTS
  From 2002 through 2012, nine hundred and seventy-three patients on the liver transplant waitlist received HPS exception points. There was no association between oxygenation and waitlist mortality among patients with HPS exception points. Transplant recipients with more severe hypoxemia had increased risk of death after liver transplantation. Rates of 3-year unadjusted post-transplantation survival were 84% for patients with PaO2 of 44.1-54.0 mm Hg vs 68% for those with PaO2 ≤ 44.0 mm Hg. In multivariable Cox models, transplant recipients with an initial room-air PaO2 ≤ 44.0 mm Hg had significant increases in post-transplantation mortality (hazard ratio = 1.58; 95% confidence interval [CI]: 1.15-2.18) compared with those with a PaO2 of 44.1-54.0 mm Hg. Overall mortality was significantly lower among waitlist candidates with HPS exception points than those without (hazard ratio = 0.82; 95% CI: 0.70-0.96), possibly because patients with HPS have a reduced risk of pre-transplantation mortality and similar rate of post-transplantation survival.
  
  
  CONCLUSIONS
  Although there was no association between pre-transplantation oxygenation and waitlist survival in patients with HPS Model for End-Stage Liver Disease exception points, a pre-transplantation room-air PaO2 ≤ 44.0 mm Hg was associated with increased post-transplantation mortality. HPS Model for End-Stage Liver Disease exception patients had lower overall mortality compared with others awaiting liver transplantation, suggesting that the appropriateness of the HPS exception policy should be reassessed.
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Clinical Center for Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: david.goldberg@uphs.upenn.edu.
authors.forename: David S
authors.initials: DS
authors.lastname: Goldberg
authors.affiliation: Division of Gastroenterology, Department of Medicine, Hershey Medical Center, Hershey, Pennsylvania.
authors.forename: Karen
authors.initials: K
authors.lastname: Krok
authors.affiliation: Division of Gastroenterology, Hepatology, and Nutrition, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: Sachin
authors.initials: S
authors.lastname: Batra
authors.affiliation: Department of Hepatology, Baylor University Simmons Transplant Institute, Dallas, Texas.
authors.forename: James F
authors.initials: JF
authors.lastname: Trotter
authors.affiliation: Clinical Center for Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; Pulmonary, Allergy, and Critical Care Division, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Kawut
authors.affiliation: Division of Gastroenterology, Hepatology, and Nutrition, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Fallon
mesh_terms: D016208:Databases, Factual; D005260:Female; D020065:Hepatopulmonary Syndrome / Q000150:complications* / Q000175:diagnosis / Q000401:mortality / Q000628:therapy; D006801:Humans; D000860:Hypoxia / Q000209:etiology / Q000401:mortality; D016031:Liver Transplantation / Q000009:adverse effects / Q000401:mortality; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D018579:Patient Selection; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D009927:Tissue and Organ Procurement; D016896:Treatment Outcome; D014481:United States; D014850:Waiting Lists / Q000401:mortality
keywords: Allocation; Gas Exchange; MELD; UNOS