Long-term Kidney Outcomes in Patients With Acquired Thrombotic Thrombocytopenic Purpura

Introduction Severe acute kidney injury (AKI) and chronic kidney disease (CKD) are considered to be uncommon in patients with acquired thrombotic thrombocytopenic purpura. However, a recent case series from a tertiary care hospital indicated that 54 (59%) of 92 patients with thrombotic thrombocytopenic purpura presented with AKI; 14 (15%) required dialysis; and 12 (22%) of the 54 patients had CKD at follow-up. Methods In this prospective analysis of 78 patients diagnosed with their first episode of thrombotic thrombocytopenic purpura and enrolled in the Oklahoma Thrombotic Thrombocytopenic Purpura Registry from 1995 to 2015, we assessed AKI at diagnosis using Kidney Disease: Improving Global Outcomes criteria, and CKD at follow-up as defined by estimated glomerular filtration rate <60 ml/min per 1.73 m2 determined by the Chronic Kidney Disease-Epidemiology Collaboration equation. Results Forty-five (58%) patients had AKI; 8 (10%) had stage 3 AKI, and 3 (4%) required dialysis. AKI was not associated with the patients' demographic or presenting clinical features. Three of the 8 patients with stage 3 AKI died; among the 5 survivors, estimated glomerular filtration rate was 77 to 107 ml/min per 1.73 m2 (median, 92) with median follow-up of 8.1 years. Among all 62 surviving patients who have had follow-up serum creatinine measurements, 4 (6%) had CKD with median follow-up of 6.4 years. AKI was not associated with the occurrence of CKD (P = 0.74). No patients have required continuing renal replacement therapy. Discussion In this population-based prospective cohort of consecutive patients with thrombotic thrombocytopenic purpura, without selection or referral bias, severe AKI and CKD are uncommon.