Validating Lactate Dehydrogenase (LDH) as a Component of the PLASMIC Predictive Tool (PLASMIC-LDH)

C.C.K. Liam^1,2,3, J.Y.-H. Tiao^1,2, Y.Y. Yap³, J. Sathar³, Y.L. Lee⁴, S. McRae⁵, A. Davis⁶, J. Curnow⁷, R. Bird⁸, P. Choi⁹, P. Angchaisuksiri¹⁰, S.L. Tien¹¹, J.C.M. Lam¹², D. Oh¹³, J.S. Kim¹⁴, S.-S. Yoon¹⁵, R. Wong¹⁶, S. Macpherson^17,18, E. Merriman^19,20, R.I. Baker^1,2

¹Perth Blood Institute, West Perth, Australia, ²Western Australian Centre for Thrombosis and Haemostasis (WACTH), Murdoch, Perth, Australia, ³Department of Haematology, Hospital Ampang, Ampang, Malaysia, ⁴Centre for Clinical Trials, Hospital Ampang, Ampang, Malaysia, ⁵Northern Cancer Service, Launceston, Australia, ⁶The Alfred Hospital, Melbourne, Australia, ⁷Westmead Hospital, Westmead, New South Wales, Australia, Westmead, Australia, ⁸Princess Alexandra Hospital, Woolloongabba, Australia, ⁹The Canberra Hospital, Canberra, Australia, ¹⁰Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, ¹¹Singapore General Hospital, Singapore City, Singapore, ¹²KK Women's and Children's Hospital, Singapore City, Singapore, ¹³CHA Bundang Medical Center, CHA University, Seongnam, Korea, Republic of, ¹⁴Yonsei University College of Medicine, Seoul, Korea, Republic of, ¹⁵Seoul National University Hospital, Seoul, Korea, Republic of, ¹⁶The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, N.T, Hong Kong, SAR of China, ¹⁷Department of Haematology, Christchurch Hospital, Christchurch, New Zealand, ¹⁸Canterbury District Health Board, Christchurch, New Zealand, ¹⁹North Shore Hospital, Auckland, New Zealand, ²⁰Waitemata District Health Board, Auckland, New Zealand

Abstract Number: PB0848

Meeting: ISTH 2021 Congress

Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » ADAMTS13 and TTP

Background: The PLASMIC score is a convenient tool for predicting severe thrombotic thrombocytopenic purpura (TTP) with ADAMTS-13 activity of < 10%. Lactate dehydrogenase (LDH) is widely used as a marker of haemolysis in TTP monitoring and could be a useful alternative for the lysis marker component of the PLASMIC score.

Aims: The purpose of this study is to validate the PLASMIC score in a multi-centre Asia Pacific region and examine LDH as a putative replacement lysis marker at presentation.

Methods: Records of patients with suspected thrombotic microangiopathy (TMA) in the Asia-Pacific Microangiopathy and Thrombosis (APMAT) Network biobank. The ADAMTS 13 activity with clinical and laboratory components of the PLASMIC score was obtained. Patients with incomplete results of ADAMTS-13 activity and/or PLASMIC scores were excluded. In all patients, the PLASMIC score and an alternative PLASMIC-LDH score, in which LDH replaced the traditional markers of lysis were calculated. We generated a receiver operator characteristics (ROC) curve and compared the predictive ability of each model.

Results: Of the 72 patients reviewed, 46 patients fulfilled the inclusion criteria of which 34 had ADAMTS 13 activity < 10%. When dichotomized at intermediate-high risk (scores 5-7) and low risk (scores 0-4), the PLASMIC score had a sensitivity of 97.1%, a specificity of 58.3% with a positive predictive value (PPV) of 86.8%, and negative predictive value (NPV) of 87.5%. The PLASMIC-LDH had a sensitivity of 97.1%, a specificity of 33.3% with a PPV of 80.5%, and an NPV of 80.0%.

Conclusions: Our study validated the original PLASMIC score as an excellent predictive tool for severe TTP in the APMAT cohort and may be used in patients presenting with TMA. Substituting LDH into the score (PLASMIC-LDH), did not significantly impair the predictive ability of the PLASMIC score, albeit with markedly reduced specificity. Further validation studies will enhance the modified predictive score.

To cite this abstract in AMA style:

Liam CCK, Tiao JY-, Yap YY, Sathar J, Lee YL, McRae S, Davis A, Curnow J, Bird R, Choi P, Angchaisuksiri P, Tien SL, Lam JCM, Oh D, Kim JS, Yoon S-, Wong R, Macpherson S, Merriman E, Baker RI. Validating Lactate Dehydrogenase (LDH) as a Component of the PLASMIC Predictive Tool (PLASMIC-LDH) [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/validating-lactate-dehydrogenase-ldh-as-a-component-of-the-plasmic-predictive-tool-plasmic-ldh/. Accessed December 1, 2022.

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