THE EFFECT OF TRANSPLANT CENTER VOLUME ON CARDIAC TRANSPLANT OUTCOME - A REPORT OF THE ITED-NETWORK-FOR-ORGAN-SHARING-SCIENTIFIC-REGISTRY

Objective.-The number of cardiac transplant programs continues to incr ease despite no increase in the number of hearts available for transpl antation. As a result, the majority of heart transplant centers perfor m extremely small numbers of transplant operations annually. To determ ine the effect of small transplantation volume on transplant outcome, the following study was performed. Design.-Using the Scientific Regist ry of the United Network for Organ Sharing, all cardiac transplant pro cedures from October 1987 through December 1991 were analyzed to deter mine whether center volumes affected cardiac transplant outcome.Patien t survival rates for each center were determined, and the survival rat es were modeled for the following patient variables: first transplanta tion or retransplantation, patient condition at the time of transplant ation, patient underlying cardiac disease (congenital vs all others), and time. Setting.-All cardiac transplant centers in the United States were included in the analysis. Patients.-All patients undergoing card iac transplantation in the United States from October 1987 through Dec ember 1991 were included in the analysis. Main Outcome Measure.-The pr imary end point in this analysis was mortality. Results.-Throughout th e entire study, of the 150 cardiac transplant centers, 35.3% of the ce nters were performing fewer than five cardiac transplantations per yea r, 53.3% were performing fewer than nine transplantations per year, an d 61.3% were performing fewer than 12 transplantations per year, the m inimum required for Medicare payment eligibility. Using the modeled su rvival rates, the risk of mortality decreased to a basal level in thos e centers performing between eight and 10 transplant operations per ye ar. In centers performing fewer than nine transplantations, mortality increased sharply and exponentially. Dividing centers into those that performed nine or more transplantations per year (70 centers) and fewe r than nine transplantations per year (80 centers), the increased risk of mortality at 1 month and 12 months was 40.3% and 33.1%, respective ly, in centers performing fewer than nine cardiac transplantations per year (P<.001). Once the threshold of nine transplant procedures was m et, those centers that were eligible for Medicare payment did not have significantly better survival than those centers not eligible for Med icare coverage. Conclusions.-These data demonstrate that the risk of m ortality at early and intermediate time points is substantially higher in low-volume cardiac transplant centers, which make up more than hal f of the centers performing cardiac transplantation in the United Stat es.