Plasmic 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.
References
- Bendapudi PK, Hurwitz S, Fry A, et al. derivation and external validation of the plasmic score for rapid assessment of adults with thrombotic microangiopathies: a cohort study. Lancet Haematol. 2017;4(4):e157-e164.
- Li A, Khalighi PR, Wu Q, Garcia DA. External validation of the PLASMIC score: a clinical prediction tool for thrombotic thrombocytopenic purpura diagnosis and treatment. Thromb Haemost 2018;16(1):164-169
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.
References
- Coppo P, et al. PLoS One. 2010;5(4):e10208
- Bendapudi PK, et al. Lancet Haematol. 2017;4(4):e157-e164
