Introduction: Renal grafts used in simultaneous kidney liver (SLK) transplants are allocated by arbitrary clinical criteria without entering the kidney allocation algorithm. The goal of this study was to evaluate differences between transplant outcomes of renal allografts allocated to SLK patients in comparison to those entering the kidney allocation algorithm in kidney only (KI) patients.

Methods: 2000-2014 UNOS data was queried for matched donor pairs in which one kidney was allocated to a patient with end-stage renal failure for a KI transplant and the other allocated to a SLK patient. Patients receiving additional transplant allografts were excluded. Patients were subdivided based on renal allograft quality according to kidney donor profile index (KDPI) allocation system: KDPI<20%, KDPI 20-34%, KDPI 35-85%, KDPI>85%. Demographic data and transplant outcomes (patient and death censored graft survival) were compared between SLK and KI recipients.

Results: 2218 donor pairs were included in which 3.6% had KDPI<20%, 16.6% had KDPI 20-34%, 60.7% had KDPI 35-84% and 19.1% had KDPI>85%. SLK recipients were older (p<0.001), predominately Caucasian (p<0.001), had higher HLA mismatch (p<0.009), lower rates of pre-transplant dialysis (p<0.001), shorter wait-list time (p<0.001), and shorter cold ischemia times (p<0.047). One, five, and ten-year patient and graft survival in both SLK and KI patients decreased with increasing KDPI. KI patients had better patient survival compared to SLK groups for KDPI 20-34% (97.7%, 87.4%, 68.4% vs. 90.4%, 77.3%, 62.8% p =0.002), KDPI 35-85% (97.4%, 86.0%, 68.7% vs. 86.5%, 71.1%, 54.6%, p<0.001), KDPI>85% (92.5%, 82.5%, 50.3% vs. 77.0%, 61.3%, 40.3%, p<0.001) but not KDPI<20% (p=0.487). SLK patients had better 1 and 5-year death censored graft survival than KI patients for KDPI 20-34%, (94.2%, 81.3% vs. 94.2%, 81.1% p=0.016), but not KDPI<20%, KDPI 35-84%, or KDPI>85%(p>0.057).

Conclusion: Our study demonstrated SLK patients have comparable death-censored graft survival but overall lower patient survival when compared to matched donor KI patients. Among SLK recipients greater patient survival is achieved by those patients that received a lower KDPI kidney. These findings highlight the importance of appropriate guidelines for renal allograft allocation to ensure fair distribution of this scarce resource.

CITATION INFORMATION: Zens T, Danobeitia J, Stahler P, Leverson G, Redfield III R, D'Alessandro A, Fernandez L. A UNOS Database Analysis of Patient Outcomes from Kidney Alone versus Simultaneous Kidney Liver Transplants Utilizing Matched Donor Pairs. Am J Transplant. 2017;17 (suppl 3).

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