Validation Of The Plasmic Score For Predicting Adamts13 Activity < 10% In Patients Admitted To Hospitals In Alberta With Suspected Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic microangiopathy (TMA), characterized by widespread intravascular thrombosis. Diagnosis of TTP is confirmed by a deficiency in ADAMTS13. However, given the urgency of prompt diagnosis and delayed turnaround time of ADAMTS13 assay in most labs, initial diagnosis is based on clinical acumen. Suspected TTP is empirically treated with plasma exchange (PLEX), which, while beneficial in TTP, may delay appropriate treatment for similar disorders. The PLASMIC score was developed by Bendapudi et al. (Lancet Hematology 2017) to utilize clinical signs and investigations to predict which patients had an ADAMTS13 score < 10%, and therefore TTP, who require PLEX. Validation studies have shown a very high sensitivity (90-98%) and high specificity (46-92%), although these studies included an enriched population with available ADAMTS13 assay results (Jajosky et al. Transfusion and Apheresis Science, 2017, Li et al. Journal of Thrombosis and Hemostasis 2018). The purpose of this study is to validate the PLASMIC score using a Canadian population of suspected TTP regardless if ADAMTS13 was ordered, and compare it to clinical gestalt.