Effect of Pre-Transplant Sensitization on Kidney Allograft Survival Following Simultaneous Liver and Kidney Transplantation: A Decade of Experience from an Academic Transplant Center.

BACKGROUND: There are conflicting data regarding the impact of pre-transplant sensitization on kidney allograft outcomes following simultaneous liver-kidney (SLK) transplantation. METHODS: This was a single-center, retrospective study of adult SLK transplant recipients during the decade from 2010 to 2020. Patients were classified based on complement dependent cytotoxicity crossmatching (CDC-CXM) as well as the presence of donor specific antibodies (DSA) and followed until study conclusion on January 1, 2021. Cox-proportional hazards modeling was performed to identify clinical variables associated with combined patient and allograft survival as well as biopsy proven kidney rejection (BPAR). RESULTS: A total of 90 patients were included in the study (16 positive CDC-CXM and 31 with DSA). Overall patient and allograft survival was 91.1% at 1-year and 68.9% at study conclusion after a median of 4.4 years, with corresponding death-censored kidney survival of 98.8% and 91.2%. In the multivariable analysis, a positive CDC-CXM (HR = 3.79; 95% CI 1.70-8.46) but not pre-formed DSA was associated with patient and graft loss. BPAR occurred in 12 patients (13.3%) and was higher among patients with DSA >5,000 (HR = 3.69; 95% CI 1.14-11.98), although this did not impact overall kidney survival. DSA cleared in 85% of patients following SLK transplant but persisted in three patients with DQ-specific antibodies. CONCLUSIONS: A positive CDC-CXM but not the presence of pre-formed DSA was associated with worse outcomes following SLK transplantation, with overall kidney survival primarily driven by death with a functioning allograft. DSA >5,000 MFI increased the risk for BPAR, and DSA to the class II DQ antigen were incompletely cleared following SLK transplant; however, overall kidney survival was not impacted.