PLASMIC and French scores for iTTP
| Clinical prediction tool . | Score components (1 point for each) . | Probability of severe ADAMTS13 deficiency . | ||
|---|---|---|---|---|
| Low . | Intermediate . | High . | ||
| PLASMIC score | Platelet count <30 × 109/L Hemolysis: reticulocytes >2.5%, undetectable haptoglobin, or indirect bilirubin >2 mg/dL No active cancer No history of solid-organ or stem cell transplant MCV <90 fL INR <1.5 Creatinine <2 mg/dL | 0-4 | 5 PLASMIC score ≥5: sensitivity, 99%; specificity; 57%; NPV, 99%; PPV, 56%13 | 6-7 PLASMIC score ≥6: sensitivity, 85%; specificity, 89%; NPV, 92%; PPV, 81%)13 |
| French score | Platelet count <30 × 109/L Serum creatinine <2.26 mg/dL Positive ANAa | 0 | 1 French score ≥1: sensitivity 98.8%; specificity 48.1%; NPV, 93.3%; PPV, 85%11 | ≥2 French score 3; sensitivity 96.9%; specificity 98.1%; NPV, 38.6%; PPV, 98.7% |
| Clinical prediction tool . | Score components (1 point for each) . | Probability of severe ADAMTS13 deficiency . | ||
|---|---|---|---|---|
| Low . | Intermediate . | High . | ||
| PLASMIC score | Platelet count <30 × 109/L Hemolysis: reticulocytes >2.5%, undetectable haptoglobin, or indirect bilirubin >2 mg/dL No active cancer No history of solid-organ or stem cell transplant MCV <90 fL INR <1.5 Creatinine <2 mg/dL | 0-4 | 5 PLASMIC score ≥5: sensitivity, 99%; specificity; 57%; NPV, 99%; PPV, 56%13 | 6-7 PLASMIC score ≥6: sensitivity, 85%; specificity, 89%; NPV, 92%; PPV, 81%)13 |
| French score | Platelet count <30 × 109/L Serum creatinine <2.26 mg/dL Positive ANAa | 0 | 1 French score ≥1: sensitivity 98.8%; specificity 48.1%; NPV, 93.3%; PPV, 85%11 | ≥2 French score 3; sensitivity 96.9%; specificity 98.1%; NPV, 38.6%; PPV, 98.7% |
The modified French score that includes only platelet count and serum creatinine is more commonly used (since ANA is rarely available at presentation) and has similar performance metrics.
ANA, antinuclear antibody; INR, international normalized ratio; MCV, mean corpuscular volume.