Digital Predictive Score

Predicts ADAMTS13 deficiency in suspected thrombotic thrombocytopenic purpura (TTP) with high discrimination

EVIDENCE APPRAISAL

The PLASMIC Score was derived by Bendapudi et al and externally validated in a study with an independent cohort of 112 consecutive hospitalized patients with suspected thrombotic microangiopathy and appropriate ADAMTS-13 testing (including 21 patients with TTP diagnosis). The PLASMIC model predicted severe ADAMTS-13 deficiency with a c statistic of 0.94 (0.88-0.98). When dichotomized at high (scores 6-7) vs. low-intermediate risk (scores 0-5), the model predicted severe ADAMTS-13 deficiency with positive predictive value 72%, negative predictive value 98%, sensitivity 90% and specificity 92%.

In the low-intermediate risk group (scores 0-5), there was no significant improvement in overall survival associated with plasma exchange. The PLASMIC Score had excellent applicability, discrimination and calibration for predicting severe ADAMTS-13 deficiency. The clinical algorithm allowed identification of a subgroup of patients who lacked a significant response to empiric treatment.

French Score

Each item is associated with one point (+1)

^aResults correspond to those of the derivation cohort and those of a validation by (French score) the bootstrap resampling technique (internal validation)^3,4 or (PLASMIC score) different samples of patients from the same institution (internal validation) or from a different institution (external validation).

^bThe French score considered patients with a thrombotic microangiopathy syndrome (which includes hemolysis with schistocytes in the definition) and assumes that there is no history of or clinical evidence for associated cancer, transplantation, or disseminated intravascular coagulopathy; so, these items are intrinsic to the score.

^cMCV was not incorporated in the French score.