The outcome of thrombotic microangiopathy in kidney transplant recipients

Abstract

Background: The outcome of kidney transplant recipients with a history of complement-mediated thrombotic microangiopathy (cTMA) and those who develop post-transplant de novo TMA (dnTMA) is largely unknown. Methods: We retrospectively studied all kidney transplant recipients with end-stage kidney disease secondary to cTMA and those who developed dnTMA, between Jan 2000 and Dec 2020 in our center. Results: We identified 134 patients, 22 with cTMA and 112 had dnTMA. Patients with cTMA were younger at the time of TMA diagnosis (age at diagnosis, 28.9 ± 16.3. vs 46.5 ± 16.0 years; P < 0.001). T-cell mediated rejection, borderline rejection, and calcineurin inhibitor toxicity were more prevalent in the first kidney transplant biopsy (P < 0.05) in the dnTMA group, and antibody-mediated rejection was more prevalent in anytime-biopsy (P = 0.027). After adjusting for potential confounders, cTMA was associated with a sixfold increase in the hazard of transplant failure during the first-year post-transplant (adjusted hazard ratio (aHR): 6.37 [95%CI: 2.17 to18.68; P = 0.001]; the aHR decreased by 0.87 (95% CI: 0.76 to 0.99: P = 0.033) per year elapsed since transplantation. Long-term allograft survival was similar in both groups. Conclusion: Post kidney transplant TMA is an important cause of poor allograft survival. More studies are needed to enhance our understanding and management of this disorder.