#768 Renal-limited thrombotic microangiopathies and hemolytic uremic syndromes, on behalf of the MATRIX consortium group

Abstract

Abstract Background and Aims Thrombotic microangiopathies (TMA) are usually associated with hematological features (RH-TMA). The epidemiology of TMA limited to kidneys (RL-TMA) is unclear. Method Patients with TMA and native kidney biopsies were identified during the 2009-2022 period in 20 French hospitals. Results RL-TMA was present in 341/757 (45%) patients and associated with lower creatinine levels (184 [115-297] vs 346 [206-626] µmol/L) than RH-TMA. RL-TMA resulted from virtually all KDIGO causes (more frequently from anti-VEGF treatment and hematological malignancy, less frequently from shiga toxin-associated hemolytic uremic syndrome (HUS), systemic sclerosis, gemcitabine and bacterial infection) but less frequently combined (≥3 causes/triggers: RL-TMA: 5%; RH-TMA: 12%). RL-TMA were associated with significantly lower major cardiovascular events (10% vs 20%), kidney replacement therapy (23% vs 43%) and death (12% vs 20%) than RH-TMA during follow-up (median: 28 (interquartile range: 7-72) months. Atypical HUS (aHUS) was found in 326 patients (RL-TMA: 43%, RH-TMA: 46%). Among the 69 patients with complement-mediated aHUS, 17 (25%) had RL-TMA and eculizumab was used in 43 (62%) (RL-TMA: 35%; RH-TMA: 71%). Among the 257 other aHUS patients, including 51% with RL-TMA, complete complement evaluation was performed in 85 (33%) (RL-TMA: 33%, RH-TMA: 33%) and eculizumab was used in 29 (11%). The effects of eculizumab were unclear. Conclusion RL-TMA represent a very high proportion of TMA patients, result from virtually all causes, including the 25% of patients with complement-mediated aHUS, and have a poor prognosis. Anti-C5 therapy is rarely used in RL-TMA, even in proven complement-mediated aHUS, and thus its effects remain to be assessed.