Validation of PLASMIC score: an academic medical center case series (2012‐present)

Abstract

BACKGROUNDThe PLASMIC score is a rapid and inexpensive tool for predicting severe ADAMTS13 deficiency (activity <10%) in patients with suspected thrombotic thrombocytopenic purpura (TTP) by analyzing seven parameters (platelet count; combined hemolysis variable; absence of active neoplasia; absence of an organ or stem‐cell transplant; mean corpuscular value; international normalized ratio; and serum creatinine). The purpose of this study was to validate the PLASMIC score at a large multi‐institutional academic medical center.METHODSAn internal database of consultations to the transfusion medicine service, which oversees therapeutic apheresis at our institution, was reviewed to identify patients who were evaluated for and/or received plasma exchange for suspected TTP. These consultations covered the time period of January 2012 to February 2019. PLASMIC scoring criteria and ADAMTS13 assay results were abstracted from the electronic medical record, the PLASMIC score was calculated, and cases stratified into risk categories (low, intermediate, high risk) based on the score value.RESULTSOf 58 patients identified, 46 met inclusion criteria, and 27 demonstrated ADAMTS13 activity <10%. Correlation of severe ADAMTS13 deficiency with risk‐stratified groups resulted in 78% sensitivity, 63% specificity, 75% positive predictive value (PPV), and 67% negative predictive value (NPV).DISCUSSIONThese findings paralleled those from validation studies performed at other institutions. They provided insufficient evidence to recommend routine use of the PLASMIC score to rule out TTP among patients at our hospitals. Nonetheless, these results reinforce the importance of early ADAMTS13 testing as a diagnostic triage tool for patients with suspected TTP.

Clinical features and neurological outcomes in pediatric immune‐mediated thrombotic thrombocytopenic purpura: A report from a large pediatric hematology center

“…Median ADAMTS13 activity was 5% (3%–6%) with a median inhibitor value of 2.4 BU (0.7–10) in 17 individuals. Median PLASMIC and FRENCH clinical prediction scores used to stratify risk for TTP were 6.5 and 2.5, respectively, falling into high‐risk category for these prediction scores 19,20 . See Table 1 for presenting labs on admission.…”

“…All patients presented with thrombocytopenia and microangiopathic hemolytic anemia on initial presentation with a median platelet count of 17 × 10 9 /L, hemoglobin 6.8 g/dl (4.6-113.9), and LDH 1940 U/L (380-11,363). Median ADAMTS13 activity was 5% (3%-6%) with a median inhibitor value of 2.4 BU (0.7-10) in 17 individuals.Median PLASMIC and FRENCH clinical prediction scores used to stratify risk for TTP were 6.5 and 2.5, respectively, falling into high-risk category for these prediction scores 19,20. See Table1for presenting labs on admission.When analyzing all TTP episodes (n = 28) in 18 patients, neurologic and renal symptoms were seen in an equal percentage (n = 21; 77%).…”

Proteinuria Increases the PLASMIC and French Scores Performance to Predict Thrombotic Thrombocytopenic Purpura in Patients With Thrombotic Microangiopathy Syndrome

“…Bendapudi et al created the PLASMIC score using two cohorts with a high prevalence of TTP (14 to 47%) and demonstrated its accuracy for TTP diagnosis (AUC 0.91-0.96) (10). Further studies with a high TTP prevalence (25 to 70%) confirmed the good diagnostic value of both the PLASMIC and French scores (23)(24)(25)(26)(27)(28)(29). However, they also included highly selected patients recruited among those that had ADAMTS13 measurement (30).…”

Evaluation of thrombotic thrombocytopenic purpura and other thrombotic microangiopathies: Lessons learned from a 14‐year retrospective study

“…Classic HUS is an infection‐related TMA often associated with Escherichia coli 0104:4 that responds to supportive care. Some classic HUS patients may require dialysis as part of the supportive care, but TPE has not been found to improve the outcome [22]. The mortality rate of the combined group of aHUS and HUS was similar to those in the TTP group and primarily treated with supportive care (after the initial TPE treatment before TTP was ruled out).…”

“…At the time of publication of the first research evaluating the PLASMIC score, few institutions were testing for ADAMTS-13 in-house. Therefore, the PLASMIC score had more utility in the setting of evaluating a patient within the first few days after presenting with signs/ symptoms of TMA/TTP without the availability of rapid ADAMTS-13 activity results [20][21][22][23]. In this study, we evaluated our 14-year experience of patients referred to the apheresis service with the clinical suspicion of TTP.…”