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Abstract: FR-PO1084

Clinical Characteristics and Renal Outcome of Patients with Thrombotic Thrombocytopenic Purpura from a Large Multicenter Cohort (USTMA Registry)

Session Information

Category: CKD (Non-Dialysis)

  • 2303 CKD (Non-Dialysis): Mechanisms


  • Klomjit, Nattawat, Division of Nephrology and Hypertension, University of Minnesota, Minneapolis, Minnesota, United States
  • Evans, Michael David, University of Minnesota Twin Cities Clinical and Translational Science Institute, Minneapolis, Minnesota, United States
  • Mazepa, Marshall, Division of Hematology, Oncology and Transplantation, University of Minnesota, Minneapolis, Minnesota, United States

Thrombotic thrombocytopenic purpura (TTP) is a rare hematological disease caused by autoimmune deficiency of ADAMTS13 and responds to urgent plasma exchange. Renal dysfunction is typically mild and several clinical scores have incorporated creatinine (Cr) level < 2.0 mg/dL to differentiate TTP from other thrombotic microangiopathies. However, renal dysfunction and outcomes are not well studied in TTP. Therefore, we used the United States Thrombotic Microangiopathies (USTMA) TTP registry, the largest US TTP registry, to evaluate clinical characteristics of patients with severe renal dysfunction at presentation and estimate loss of kidney function over time.


The USTMA TTP registry contains data on TTP episodes between 1985 to 2019 from 14 centers across the US. We compared the clinical characteristics upon presentation between patients presenting with mild (Cr ≤ 2 mg/dl) versus severe (Cr >2 mg/dl) renal dysfunction. To model eGFR loss over time with TTP episodes, we used longitudinal linear mixed-effects models.


Between 1985-2019, there were 1257 TTP episodes (771 patients) and the majority of episodes had mild renal dysfunction (n=1115, 88.7%). Compared to mild renal dysfunction, patients with severe renal dysfunction had more severe symptoms, lower platelets and higher lactate dehydrogenase (LDH). There were 285 unique patients with multiple TTP episodes to evaluate for eGFR loss over time. Overall, we found a mean slope of eGFR per year of -0.70 (95% CI −0.84, −0.56). There were no differences in eGFR slopes according to the number of TTP episodes a patient experienced. LDH level was associated with eGFR loss between episodes, with a modestly sized effect (change in eGFR per year slope 0.020 (95% CI 0.008-0.032) per 2-fold increase in LDH).


Severe renal dysfunction is uncommon in TTP but it is more likely to be present in patients with multi-organ dysfunction. Hence, existing clinical prediction scores are likely less accurate in more severe TTP episodes. Loss of eGFR over time is consistent with previous estimates of age-related eGFR, hence we conclude that subsequent TTP episodes do not significantly affect eGFR loss and likely confirms previous findings that most patients with TTP recover normal renal function with modern treatment.