Gui et al reported a simple score for the identification of a patient with refractory thrombotic thrombocytopenic purpura (TTP). The authors are from multiple institutions in China.
Patient selection: immune-mediated TTP
Outcome: refractory TTP - one or both of the following:
(1) (lack of a doubling of the platelet count after 4 days of standard therapeutic plasma exchange and steroid therapy) AND (a serum LDH > ULN);
(2) (reduction of the platelet count below the LLN of the normal reference range) AND (increased serum LDH) AND (need to restart plasma exchange after the last plasma exchange after an initial response)
Parameters:
(1) age in years
(2) hemoglobin in g/L
(3) serum creatinine in µmol/L
Parameter
Finding
Points
age in years
<= 40 years
0
41 to 60 years
1
> 60 years
2.5
hemoglobin
<= 60 g/L
2
60.1 to 100 g/L
1
> 100 g/L
0
serum creatinine
<= 106 µmol/L
0
107 to 180 µmol/
1
> 180 µmol/L
2
where:
• At the lower cutoffs there is overlapping criteria for inclusion. The values above reflect an attempt to adjust for this.
total score =
= SUM(points for all 3 parameters)
Interpretation:
• minimum score: 0
• maximum score: 6.5
Score
Risk of Refractory TTP
0 or 1
low
2 to 3.5
intermediate
>= 4.0
high
Performance:
• The area under the ROC curve is 0.89 in the derivation and 0.86 in the validation cohorts.
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