260 Immunoprotective impact of the kidney in SPK transplants - proceed with live donor kidney or wait for SPK?
Monday November 16, 2015 from 11:00 to 12:30
Room 110

Erik B Finger, United States

Assistant Professor

Erik Finger

University of Minnesota


Immunoprotective impact of the kidney in SPK transplants - proceed with live donor kidney or wait for SPK?

Erik Finger1, Ty B Dunn1, Alexandra Kukla1, Patty Liu1, David ER Sutherland1, Raja Kandaswamy1.

1Department of Surgery, University of Minnesota, Minneapolis, MN, United States

Objective:  In view of recent changes in pancreas allocation policy that have markedly reduced waiting times for SPK transplants, we sought to examine if the perceived benefits in pancreas outcomes in SPK transplants in comparison to PAK and PTA justify waiting for SPK donor rather than proceeding with live donor kidney and planned PAK.  We further hypothesized that the simultaneous same donor kidney could offer immunoprotective benefit.  To address this hypothesis we sought to determine if HLA matching between prior kidney and the current pancreas donor for PAK transplants reduced rejection or improved survival.
Methods:  Retrospective review of prospectively assembled database of 1,261 deceased donor pancreas transplants performed at a single center from 1998 to 2015.  We compared the rejection rates and graft survival of simultaneous kidney and pancreas transplants (SPK, N = 371) with pancreas after kidney transplants (PAK N = 511), pancreas transplant alone (PTA, N = 359), and simultaneous deceased donor pancreas and living donor kidney transplant (PwK, N = 41).  Outcomes assessed included acute rejection (AR) in first year and long-term death censored graft survival (overall or immune-mediated graft loss).  Standard statistical univariate (Kaplan-Meier) and multivariate (Cox Proportional Hazards Model) models were used to assess association with risk factors and outcomes.  In addition to transplant order, patient and recipient demographics, surgical approach, immunosuppressive agents, and immune profile (PRA and HLA matching) were included as potential cofounders in the initial multivariate model and excluded if non-significant.
Results:  In contrast to a rejection rate in SPK transplants of 13.8%, other transplant approaches had a much higher risk of rejection (PAK 30.6%, PTA 34.3%, and PwK 41.2%; all p < 0.001).  In the multivariate model, when compared with SPK transplants, PAK had a 2.9-fold increased risk of AR and PTA had a 3.5-fold increased risk.  PwK had a numerical risk 2.4-fold higher but failed to reach significance.
Pancreas graft survival in SPK transplants was significantly improved over other categories with mean survival time for SPK = 12.2 years compared with 8.0 years for PAK (p < 0.001), 7.4 years for PTA (p < 0.001), and 6.2 years for PwK (p = 0.013).  Immunologic graft loss was also markedly reduced in SPK compared to all other txps (p < 0.001 for all).
In a subset analysis, we compared the association of the number of HLA matches or mismatches between prior kidney and current pancreas donor with rejection rate and graft survival for PAK transplants.  We found no association with number of matches or mismatches on risk of rejection or graft survival in univariate or multivariate models (all p > 0.2).
Conclusion:  As expected, pancreas rejection rates and graft survival are improved in SPK transplants compared those without a simultaneous same donor kidney, validating previous studies.  The protective benefit of the kidney does not appear solely due to shared HLA alleles between the kidney and pancreas.  The basis for the immune benefit of SPK over PAK remains undetermined, but these findings may affect decision making for the pancreas candidate with a potential live kidney donor, especially as increased organ sharing results in decreased waiting times.

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