Simultaneous Pancreas-Kidney Versus Deceased Donor Kidney Transplant: Can a Fair Comparison be Made?

Background. Simultaneous pancreas-kidney transplantation (SPK) may provide superior patient and kidney graft survival compared with deceased donor kidney transplant alone (DD KA), not because of the addition of a pancreas transplant but because of differences in organ donor, recipient, and transplant characteristics. Methods. We performed a retrospective analysis from the scientific registry of transplant recipients database comparing patient and kidney graft survival of SPK and DID KA recipients from 1997 to 2005, segregating the DD KA recipients into (a) recipients of KA from pancreas donors (KA, P+) and (b) recipients of KA from non-pancreas donors to control for donor differences. Results. Of 8453 SPK waitlisted patients, 7952 received SPK, 101 received KA, P+, and 401 received KA from non-pancreas donors (KA, P-). Five-year kidney graft survival was not different in the SPK and KA, P+ groups (76.2% vs. 81.9%, P=0.15) and was significantly better than the KA, P- group (64.3%, SPK vs. KA, P-, P=0.002; KA, P+ vs. KA, P-, P=0.01). When controlling for recipient and transplant differences by multivariate analysis, KA, P+ transplant was associated with a 50% reduction in risk for kidney graft loss compared with SPK. Conclusions. Donor, recipient, and transplant differences exist when comparing SPK to DID KA that bias outcomes in favor of SPK and limit conclusions regarding superior graft and patient survival.