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Abstract: TH-PO501

PLASMIC Score to Aid Diagnosis of Atypical Hemolytic Uremic Syndrome: A Post Hoc Analysis of Data From C5 Inhibitor Trials

Session Information

Category: Glomerular Diseases

  • 1303 Glomerular Diseases: Clinical‚ Outcomes‚ and Trials

Authors

  • Uriol Rivera, Miguel, Glomerular Diseases Unit, Son Espases University Hospital, Palma de Mallorca, Spain
  • Avila Bernabeu, Ana Isabel, Nephrology Department, Dr Peset University Hospital, Valencia, Spain
  • Makar, Robert, Harvard Medical School, Boston, Massachusetts, United States
  • Booth, John, CTI Clinical Trial & Consulting Services, Covington, Kentucky, United States
  • Ernst, Frank R., CTI Clinical Trial & Consulting Services, Covington, Kentucky, United States
  • Comas, Angels, Alexion, AstraZeneca Rare Disease, Barcelona, Spain
  • Gasteyger, Christoph, Alexion, AstraZeneca Rare Disease, Zurich, Switzerland
  • Lum, Ching, Alexion, AstraZeneca Rare Disease, Boston, Massachusetts, United States
  • Tomazos, Ioannis, Alexion, AstraZeneca Rare Disease, Boston, Massachusetts, United States
  • Wang, Yan, Alexion, AstraZeneca Rare Disease, Boston, Massachusetts, United States
  • Bendapudi, Pavan Kasi, Harvard Medical School, Boston, Massachusetts, United States
Background

Thrombotic microangiopathies (TMAs) are rare disorders presenting as thrombocytopenia, microangiopathic hemolytic anemia and organ damage. Atypical hemolytic uremic syndrome (aHUS) is a complement-mediated TMA, with/without a trigger. aHUS is diagnosed by excluding thrombotic thrombocytopenic purpura (TTP) and other TMAs. PLASMIC scores (PSs) can facilitate earlier diagnosis of severe ADAMTS13 deficiency. In suspected TTP cases, a PS (min–max: 0–7, 7 components; see Figure legend) is calculated. A score of ≥6 suggests a high probability of ADAMTS13 activity <10% and TTP. This study aimed to understand PS distribution in aHUS patients and its importance in assisting earlier diagnosis and appropriate treatment.

Methods

PSs were calculated for patients with aHUS from the safety set of eculizumab (NCT01522170) and ravulizumab (NCT02949128) trials, using the first measure of PS components at screening. Relative and cumulative distributions of PSs were calculated.

Results

PS distributions were similar in both trials, with all patients scoring between 3–7 and ~50% scoring 4 (Figure). Scores 3–5, indicating probable aHUS rather than TTP, were observed in 86% of eculizumab patients and 88% of ravulizumab patients. Across PS components, platelet count and creatinine thresholds were met by the fewest patients (≤22.2%).

Conclusion

This analysis shows that PS<6 is observed in most patients with confirmed aHUS. However, a PS≥6 does not completely exclude aHUS. Assessing ADAMTS-13 activity remains essential to accurately distinguish between TTP and aHUS.

Funding

  • Commercial Support