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    Patent Pending

    PLASMIC Score for TTP

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

    INSTRUCTIONS

    Use in hospitalized adult inpatients with suspected thrombotic thrombocytopenic purpura (TTP) who might benefit from early initiation of plasma exchange while awaiting ADAMTS-13 results. Do not use in patients who have already undergone plasma exchange (i.e., intermediate and high risk groups, in whom therapeutic plasma exchange must be initiated immediately).

    When to Use
    Pearls/Pitfalls
    Why Use

    • Hospitalized adult inpatients with suspected thrombotic thrombocytopenic purpura (TTP) who might benefit from early initiation of plasma exchange while awaiting ADAMTS-13 results. 

    • Do not use in patients who have already undergone plasma exchange (i.e., intermediate and high risk groups, in whom therapeutic plasma exchange must be initiated immediately).

    • TTP can have very nonspecific symptoms, so clinical suspicion must be high. Generally, very low platelets and hemolytic anemia are TTP until proven otherwise.

    • Has high sensitivity to rule out TTP and may help distinguish TTP from a broad range of thrombotic microangiopathies.

    • Not validated for pediatric patients.

    • Samples for ADAMTS-13 level and ADAMTS-13 inhibitor must be drawn before initiation of any therapy (results may take a few days or longer, depending on the laboratory workflow).

    • Helps distinguish TTP from other causes of thrombotic microangiopathy.

    • ADAMTS-13 confirmatory testing takes several days, so a clinical score can help clarify the clinical picture and aid in decisions to initiate treatment.

    • Starting plasma exchange early in intermediate and high risk patients improves survival (mortality for untreated TTP is >90%).

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    Result:

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    Next Steps
    Evidence
    Creator Insights
    Dr. Pavan K. Bendapudi

    From the Creator

    Why did you develop the PLASMIC Score for TTP? Was there a particular clinical experience or patient encounter that inspired you to create this tool for clinicians?

    Within hematology, TTP represents a "sweet spot" for the development of a bedside diagnostic score: it is a lethal disease requiring immediate initiation of therapy but for which the gold standard diagnostic test takes 3-5 days to result. Given this situation, Robert Makar and I decided to leverage our institution's electronic medical record system to put together a curated cohort of TTP patients and try to identify common characteristics that could be used in a diagnostic score.

    What pearls, pitfalls and/or tips do you have for users of the PLASMIC Score for TTP? Do you know of cases when it has been applied, interpreted, or used inappropriately?

    The biggest mistake that clinicians make is trying to apply the score to the wrong population. The PLASMIC Score is intended for use only in patients with thrombocytopenia (platelets <150) and evidence of MAHA (schistocytes) on peripheral smear.

    Other tips: 

    1. Use the earliest lab value available for each parameter. Do not use any value drawn after ≥72 hrs of hospitalization.

    2. Combined hemolysis parameter: reticulocyte count >2.5 OR indirect bilirubin >2.0 OR haptoglobin undetectable. If any of these are positive, assign one point.

    3. The PLASMIC Score is intended to support, not replace, clinical judgment. 

    What recommendations do you have for doctors once they have applied the PLASMIC Score for TTP? Are there any adjustments or updates you would make to the score based on new data or practice changes?

    A patient's PLASMIC Score can be used to risk stratify that individual for further workup and treatment. We recommend a cutoff of 5, i.e. score <5 generally does not require further workup, score ≥5 usually requires ADAMTS13 to be sent along with expert consultation. For more information, please see Bendapudi et al 2017.

    Any other research in the pipeline that you’re particularly excited about?

    We continue to leverage our dataset to answer important clinical questions in the field of TTP and allied disorders, including other forms of thrombotic microangiopathy. We are also initiating a translational research program in which we are studying specimens from patients with TTP to better understand what predisposes people to TTP and how the disease may be prevented.

    About the Creator

    Pavan K. Bendapudi, MD, is an assistant professor of medicine at Harvard Medical School. Together with Dr. Robert Makar, he is co-principal investigator of the Harvard Thrombotic Microangiopathies Research Collaborative, an interdisciplinary, multi-institutional consortium that studies TTP and allied disorders. Dr. Bendapudi’s primary research is focused on humoral coagulation factors and the mechanisms underlying hemostatic and thrombotic disease.

    To view Dr. Pavan K. Bendapudi's publications, visit PubMed

    Are you Dr. Pavan K. Bendapudi? Send us a message to review your photo and bio, and find out how to submit Creator Insights!
    MDCalc loves calculator creators – researchers who, through intelligent and often complex methods, discover tools that describe scientific facts that can then be applied in practice. These are real scientific discoveries about the nature of the human body, which can be invaluable to physicians taking care of patients.
    Content Contributors
    • Alex Lazo, MD
    Reviewed By
    • Fatima Aldarweesh, MD
    About the Creator
    Dr. Pavan K. Bendapudi
    Are you Dr. Pavan K. Bendapudi?
    Content Contributors
    • Alex Lazo, MD
    Reviewed By
    • Fatima Aldarweesh, MD