Center effect.

1. The center effect persists through the period studied--transplants performed in 1983 and 1984. Consistent differences remain in outcome as measured by one-year graft survival. After discounting statistical variation, the extreme difference is approximately 40-50% for first grafts from cadaver donors. 2. The magnitude of the differences remains when cyclosporine is used. 3. Centers differ with respect to factors generally considered related to graft outcome, but the differences account at most for a small fraction of the differences between success rates. 4. Results were ambiguous as to whether the center effect applied to grafts from HLA-identical siblings. 5. The center effect is not entirely confined to the pre- and early posttransplant periods, since differences remain among grafts functioning three months posttransplant. Differences diminished, however, particularly among the centers with higher graft survival rates. 6. Factors not considered in the study are those relating to care after transplant and general medical risk assessments prior to transplant.