title: Post-heart transplant survival is inferior at low-volume centers across all risk strata.
abstract: BACKGROUND
  Previous studies have demonstrated a relationship between increasing center volume and cardiac transplant outcomes. The purpose of this study was to confirm a relationship between post-heart transplant outcomes and center experience and to determine whether this relationship persists among low- and high-risk heart transplant recipient-donor pairs.
  
  
  RESULTS
  The United Network for Organ Sharing (UNOS) provided deidentified patient-level data. Analysis included 8029 heart transplant recipients aged ≥18 years and transplanted between January 1, 2001 and December 31, 2006 with follow-up available through February 3, 2009. The primary outcome was observed 1-year posttransplant graft survival. Multivariable logistic regression was used to calculate expected 1-year survival for recipients. Threshold analysis identified 3 discrete risk groups of transplant recipients: high-risk, moderate-risk, and low-risk. Three discrete risk strata for center volume: low (<10.5 recipients/yr), intermediate (10.5 to 47 recipients/yr), and high (>47 recipients/yr) were also identified. χ(2) test was used to compare 1-year survival at low- and intermediate- with high-volume centers. In multivariable logistic regression analysis, annual center volume was significantly associated with posttransplant graft survival at 1 year (odds ratio [OR]=0.995, 0.992 to 0.999; P=0.010) and primary graft failure (OR=0.985, 0.972 to 0.997; P=0.015), but not stroke (OR=0.996, 0.990 to 1.003; P=0.295), infection (OR=1.001, 0.998 to 1.003; P=0.613), or dialysis (OR=1.001, 0.997 to 1.005; P=0.522). Log-rank test demonstrated significant difference in survival between volume groups with respect to high-risk (P=0.0032) and low-risk (P=0.00415), but not moderate-risk (P=0.128) patients.
  
  
  CONCLUSIONS
  A direct relationship existed between increasing center volume and improved graft survival. Across all recipient-donor pair risk strata, posttransplant graft survival at 1 year was significantly lower at low-volume centers. The volume-outcomes relationship was strongest in the highest-risk recipient-donor category.
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, College of Physicians and Surgeons, Columbia University, New York, NY, USA. mr2143@columbia.edu
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Russo
authors.forename: Alexander
authors.initials: A
authors.lastname: Iribarne
authors.forename: Rachel
authors.initials: R
authors.lastname: Easterwood
authors.forename: Ali N
authors.initials: AN
authors.lastname: Ibrahimiye
authors.forename: Ryan
authors.initials: R
authors.lastname: Davies
authors.forename: Kimberly N
authors.initials: KN
authors.lastname: Hong
authors.forename: Deborah D
authors.initials: DD
authors.lastname: Ascheim
authors.forename: Annetine C
authors.initials: AC
authors.lastname: Gelijns
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Naka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006085:Graft Survival; D016027:Heart Transplantation / Q000401:mortality*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D014019:Tissue Donors; D014184:Transplantation, Homologous; D014481:United States