Coppo et al developed a score for identifying a patient with severe acquired ADAMTS13 deficiency and thrombotic microangiopathy (TMA). The authors are from the French Reference Center for Thrombotic Microangiopathies.
Patient selection: Coombs-negative microangiopathic hemolytic anemia and acute thrombocytopenia
Outcome: risk for severe acquired, immune-mediated ADAMTS13 deficiency
Parameters:
(1) serum creatinine in mg/dL
(2) platelet count in 10^9/L
(3) antinuclear antibody (ANA)
Parameter
Finding
Points
serum creatinine
<= 2.26 mg/dL (<= 200 µmol/L)
1
> 2.26 mg/dL
0
platelet count
> 30 * 10^9/L
0
<= 30 * 10^9/L
1
ANA
negative
0
positive
1
total score =
= SUM(points for all 3 parameters)
Interpretation:
• minimum score: 0
• maximum score: 3
• The higher the score the greater the risk for ADAMTS13 deficiency.
• The authors noted that patients >= 55 years of age with ADAMTS13 deficiency may have acute renal failure and an elevated serum creatinine.
Score
Risk for Severe ADAMTS13 Deficiency
0
low
1
intermediate
2 or 3
high
Performance:
• The sensitivity of >= 1 criteria present was 99% with specificity of 48%.
• The sensitivity of all 3 criteria present was 47% with specificity 98%.
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