1693 - Risk Factors and Outcomes of Histologic Acute Graft Pyelonephritis following Kidney Transplantation

Background: Histologic acute graft pyelonephritis (HAGPN) is a complication of kidney transplantation (KT) diagnosed serendipitously by renal biopsy.  A retrospective review of 1391 patients who underwent KT at our institution between 2008 and 2017 identified 46 cases (cumulative incidence 5%).  Rejection was present in 50% of biopsies demonstrating HAGPN, complicating management.  The aims of this study were to identify risk factors and outcomes of HAGPN. 

Methods: Recipient, donor, operative and post-transplant characteristics of 46 cases of HAGPN and 138 controls randomly selected from the 1345 patients who underwent KT between 2008 and 2017 were assessed in univariable and multivariable Cox regression models. Associations of HAGPN with death or graft failure were assessed in univariable models.

Results: In univariable analysis, characteristics associated with increased risk of HAGPN in order of decreasing hazard ratio (HR) were rejection (HR 10.82, 5.66-20.72), urinary tract infections (UTI) or asymptomatic bacteriuria (ASB)  (HR 6.28, 3.43-11.50), urologic malfunction (UM) within 30 days of KT,  (HR 5.34, 2.85-10.02), less than 4 matches at HLA A/B/DR loci (HR 3.74, 1.19-11.76), delayed graft function (DGF) (HR 2.1, 1.47-3.00), basiliximab induction (HR 1.59, 1.05-2.42), diabetes mellitus (DM) at KT (HR 1.52, 1.07-2.16), operative time (HR 1.11, 1.03-1.19) and cold ischemic time (CIT) (HR 1.05, 1.02-1.06). UM, rejection and UTI or ASB were the most significant risk factors based on clinical and statistical importance, and after adjusting for them, DM, transplant type, CIT, ureteral stent placement and DGF remained significant risk factors. In univariable analysis, ureteral stent placement at transplant (HR 0.60, 0.43-0.88) and living-related donor (HR 0.18, 0.04-0.78) were each associated with reduced risk of HAGPN which persisted after multivariable analysis. In univariable analysis, HAGPN was associated with death (HR 17.04, 7.93-39.31) and graft failure (HR 3.77, 1.73, 8.20).

Conclusion: HAGPN is an infrequent, unanticipated, clinically significant complication of renal transplantation. Post-transplant dysfunction of the allograft collection system may be a modifiable risk factor.