title: Increased short- and long-term mortality at low-volume pediatric heart transplant centers: should minimum standards be set? Retrospective data analysis.
abstract: OBJECTIVE
  The relationship between volume and outcome in many complex surgical procedures is well established.
  
  
  BACKGROUND
  No published data has examined this relationship in pediatric cardiac transplantation, but low-volume adult heart transplant programs seem to have higher early mortality.
  
  
  METHODS
  The United Network for Organ Sharing (UNOS) provided center-specific data for the 4647 transplants performed on patients younger than 19 years old, 1992 to 2007. Patients were stratified into 3 groups based on the volume of transplants performed in the previous 5 years at that center: low [<19 transplants, n = 1135 (24.4%)], medium [19–62 transplants, n = 2321(50.0%)], and high [≥63 transplants, n= 1191 (25.6%)]. A logistic regression model for postoperative mortality was developed and observed-to-expected (O:E) mortality rates calculated for each group.
  
  
  RESULTS
  Unadjusted long-term survival decreased with decreasing center volume (P<0.0001). Observed postoperative mortality was higher than expected at low-volume centers [O:E ratio 1.39, 95% confidence interval (CI) 1.05–1.83]. At low volume centers, high-risk patients (1.34, 0.85–2.12)--especially patients 1 year old or younger (1.60, 1.07–2.40) or those with congenital heart disease (1.36, 0.94–1.96)--did poorly, but those at high-volume centers did well (congenital heart disease: 0.90, 0.36–1.26; age<1 year: 0.75, 0.51–1.09). Similar results were obtained in the subset of patients transplanted after 1996. In multivariate logistic regression modeling, transplantation at a low-volume center was associated with an odds ratio for postoperative mortality of 1.60 (95% CI, 1.14–2.24); transplantation at a medium volume center had an odds ratio of 1.24 (95% CI, 0.92–1.66).
  
  
  CONCLUSIONS
  The volume of transplants performed at any one center has a significant impact on outcomes. Regionalization of care is one option for improving outcomes in pediatric cardiac transplantation.
authors.affiliation: Department of Cardiothoracic Surgery, Stanford University/Lucille Packard Children's Hospital, Palo Alto, California, USA.
authors.forename: Ryan R
authors.initials: RR
authors.lastname: Davies
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Russo
authors.forename: Kimberly N
authors.initials: KN
authors.lastname: Hong
authors.forename: Seema
authors.initials: S
authors.lastname: Mital
authors.forename: Ralph S
authors.initials: RS
authors.lastname: Mosca
authors.forename: Jan M
authors.initials: JM
authors.lastname: Quaegebeur
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Chen
mesh_terms: D002648:Child; D016027:Heart Transplantation / Q000401:mortality* / Q000592:standards / Q000706:statistics & numerical data*; D006761:Hospitals / Q000592:standards / Q000706:statistics & numerical data*; D006801:Humans; D007902:Length of Stay; D016017:Odds Ratio; D011183:Postoperative Complications; D016016:Proportional Hazards Models; D012307:Risk Factors; D015996:Survival Rate; D014019:Tissue Donors