THE VARIATION AMONG TRANSPLANT CENTER RESULTS IN THE UNITED KINGDOM AND IRELAND FROM 1977 TO 1981

Abstract

An analysis of pooled data from transplants performed between 1977 and 1981 in 29 centers throughout the United Kingdom and Ireland revealed that the pattern of loss varied according to cause and postoperative time. Loss from rejection was characterized by a bimodal pattern in which early (0-25 days) and late (26-100 days) peaks of rejection were distinguishable. Rejected second transplants exhibited this phenomenon more than first transplants, and the loss was proportionately greater during the early period, suggesting that prior sensitization played an important role. Graft loss from technical causes and recipient death showed distinctly different patterns of loss. These findings suggested that, when possible, transplant survival statistics should be analyzed separately according to postoperative time and cause of loss. In applying these preliminary observations of the pooled data to a comparative study of the results in the different centers it was noted that such comparisons could be substantially affected by random variability in estimates of actuarial survival rates. Therefore, a simple method of ranking was developed in which centers were allocated to high or low survivorship categories, or to an indeterminate category when the standard error in estimated actuarial survival was relatively large. Whereas the variation in loss rate from death with a functioning transplant (DWFT) was found to be indistinguishable from random variability, both nonimmunological failure (NIF) and immunological failure (IF) of the graft were found to be legitimate bases for ranking. Furthermore, center ranking based on IF at 0-25 days failed to exhibit a significant relationship with IF at 26-100 days, which could indicate important center differences associated with antirejection treatments during these two periods. These results showed that, ideally, time-cause parameters should be analyzed separately when comparing transplant survival statistics in different centers.