A testing approach based on the PLASMIC score may be an effective risk stratification method for patients suspected of having immune thrombotic thrombocytopenic purpura (iTTP), according to research published in the British Journal of Haematology.

The PLASMIC score assesses the likelihood of severe ADAMTS13 deficiency in patients presenting with microangiographic hemolytic anemia. Researchers evaluated use of the PLASMIC score in clinical practice to risk stratify patients with suspected iTTP and reduce iTTP-related costs.

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The researchers compared a group of patients who underwent unrestricted ADAMTS13 testing (group A; 412 patients) with another group of patients who required a preapproval of the test by the transfusion medicine service (group B; 100 patients). A PLASMIC score algorithm incorporating clinical history was used to stratify patients into low-, intermediate-, and high-risk groups.

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More patients were tested using an unrestricted approach (34.28 vs 21.30 per 100,000 inpatient admissions; P <.001), but incidence of severe ADAMTS13 deficiency (4.49 vs 5.75 per 100,000 admissions; P =.29) and mortality (0.17 vs 0.21 deaths per 100,000 admissions; P =.84) were similar between the groups. More patients in group B received therapeutic plasma exchange (TPE) compared with patients in group A (14.07 vs 9.48 per 100,000 admissions; P =.001). Most patients in group A were low-risk.

The researchers noted that “a PLASMIC score-based algorithm would have significantly decreased the proportion of patients without severe ADAMTS13 deficiency who underwent ADAMTS13 testing (86.9% vs 54.2%; P <.0001) or treatment with TPE (55.3% vs 29.2%; P <.001).”

Additionally, applying the PLASMIC score to screen patients before testing for ADAMTS13 deficiency was shown to reduce costs by 27% ($684,744) over a 12-year period. Most of the savings were derived from reducing unnecessary administration of TPE, testing of ADAMTS13, and consultations with experts.

The researchers concluded that integrating a PLASMIC score-based algorithm into clinical decision making would facilitate the early identification of high-risk patients and avoid overutilization of resources by low-risk patients.


  1. Upadhyay VA, Geisler BP, Sun L, et al. Utilizing a PLASMIC score-based approach in the management of suspected immune thrombotic thrombocytopenic purpura: a cost minimization analysis within the Harvard TMA research collaborative [published online May 26, 2019]. Br J Haematol. doi:10.1111/bjh.15932