title: Temporal trends in liver transplant centre volume in the USA.
abstract: BACKGROUND
  Although prior studies have suggested an inverse association between liver transplant centre volume and postoperative patient mortality, more recent analyses have failed to confirm this association. To date, all studies of the relationship between centre volume and outcomes in liver transplantation have been cross-sectional in design.
  
  
  OBJECTIVE
  The objective of our study was to examine temporal trends in the volume-outcomes relationship for liver transplantation.
  
  
  METHODS
  We used information obtained from the Scientific Registry of Transplant Recipients (SRTR) programme-specific data reports to examine the outcomes of adult liver transplant recipients stratified by annual centre volume. This relationship between centre volume and patient outcomes was assessed over three consecutive time periods from 2000 through 2007.
  
  
  RESULTS
  The overall 25% increase in adult liver transplant volume in the USA from 2000 to 2007 appeared to be distributed fairly equally among existing transplant centres. In the earliest time period of our analysis, high-volume centres achieved superior risk-adjusted 1-year patient outcomes compared with low-volume centres. By the third and most recent time period of the analysis, this discrepancy between the outcomes of high- and low-volume centres was no longer statistically apparent.
  
  
  CONCLUSIONS
  The relationship between centre volume and patient outcomes for liver transplantation in the USA has become less pronounced over time, suggesting that the use of procedure volume as a marker of liver transplant centre quality cannot be justified. The performance-based review process currently utilized in the USA may have contributed to this diminishing influence of centre volume on liver transplant recipient outcomes. This type of review process should be considered as a potential alternative to the volume-based referral initiatives that have been developed for other non-transplant, complex surgical procedures.
authors.affiliation: Department of Surgery, Duke University Medical Centre, Durham, NC 27710, USA.
authors.forename: Elisabeth T
authors.initials: ET
authors.lastname: Tracy
authors.forename: Kyla M
authors.initials: KM
authors.lastname: Bennett
authors.forename: Emeline M
authors.initials: EM
authors.lastname: Aviki
authors.forename: Theodore N
authors.initials: TN
authors.lastname: Pappas
authors.forename: Bradley H
authors.initials: BH
authors.lastname: Collins
authors.forename: Janet E
authors.initials: JE
authors.lastname: Tuttle-Newhall
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Marroquin
authors.forename: Paul C
authors.initials: PC
authors.lastname: Kuo
authors.forename: John E
authors.initials: JE
authors.lastname: Scarborough