Prolongation of long-term kidney graft survival by a simultaneous liver transplant: the liver does it, and the heart does it too.

Background: Whereas some authors reported that kidney transplants were protected from rejection by simultaneous liver grafts, other authors failed to obtain evidence for a kidney graft-protective role for the liver.
Methods: The survival rate of 383 kidney grafts in recipients of combined kidney-liver transplants performed between 1985 and 2000 and reported to the international Collaborative Transplant Study (CTS) was analyzed and compared retrospectively with that of a matched group of control patients who were transplanted with kidneys only. In addition, 105 combined kidney-heart transplants performed during the same time period were analyzed.
Results: At 1 year, the survival rate of kidney grafts in recipients of kidney-liver transplants was significantly lower than that in kidney only recipients (P<0.0001). Subsequently, however, kidneys in kidney-liver recipients fared much better so that the success rates were virtually identical after 8 years of follow-up (62.1+/-3.5% vs. 61.9+/-2.3%, P=ns). Half-life times after the first posttransplant year were 27.6 and 14.5 years for combined or single kidney grafts, respectively, and the projected 20-year graft survival rates were 46% and 35%, respectively. The 8-year survival rate of kidney grafts in recipients of combined kidney-heart recipients was 63.5+/-6.2%, the associated half-life time 31.6 years, and the projected 20-year graft survival rate 49%.
Conclusions: The long-term kidney graft survival rate is higher in recipients of combined kidney-liver transplants than in recipients of kidney grafts only. Because the success rate is equally high in recipients of combined kidney-heart transplants, it is necessary to reexamine the hypothesis that the liver possesses a unique capacity of protecting a simultaneous kidney graft from rejection.