Blood Res.  2023 Mar;58(1):36-41. 10.5045/br.2023.2022133.

Validating lactate dehydrogenase (LDH) as a component of the PLASMIC predictive tool (PLASMIC-LDH)

• Keong Liam CC
• Tiao JYH
• Yap YY
• Lee YL
• Sathar J
• McRae S
• Davis A
• Curnow J
• Bird R
• Choi P
• Angchaisuksiri P
• Tien SL
• Mei Lam JC
• Oh D
• Kim JS
• Yoon SS
• Wong RSM
• Lauren C
• Merriman EG
• Enjeti A
• Smith M
• Baker RI

• KMID: 2541063
• DOI: http://doi.org/10.5045/br.2023.2022133

Abstract

Background
The PLASMIC score is a convenient tool for predicting ADAMTS13 activity of ＜10%. Lactate dehydrogenase (LDH) is widely used as a marker of haemolysis in thrombotic thrombocytopenic purpura (TTP) monitoring, and could be used as a replacement marker for lysis. We aimed to validate the PLASMIC score in a multi-centre Asia Pacific region, and to explore whether LDH could be used as a replacement marker for lysis.
Methods
Records of patients with thrombotic microangiopathy (TMA) were reviewed. Patients’ ADAMTS13 activity levels were obtained, along with clinical/laboratory findings relevant to the PLASMIC score. Both PLASMIC scores and PLASMIC-LDH scores, in which LDH replaced traditional lysis markers, were calculated. We generated a receiver operator characteristics (ROC) curve and compared the area under the curve values (AUC) to determine the predictive ability of each score.
Results
46 patients fulfilled the inclusion criteria, of which 34 had ADAMTS13 activity levels of ＜10%. When the patients were divided into intermediate-to-high risk (scores 5‒7) and low risk (scores 0‒4), the PLASMIC score showed a sensitivity of 97.1% and specificity of 58.3%, with a positive predictive value (PPV) of 86.8% and negative predictive value (NPV) of 87.5%. The PLASMIC-LDH score had a sensitivity of 97.1% and specificity of 33.3%, with a PPV of 80.5% and NPV of 80.0%.
Conclusion
Our study validated the utility of the PLASMIC score, and demonstrated PLASMIC-LDH as a reasonable alternative in the absence of traditional lysis markers, to help identify high-risk patients for treatment via plasma exchange.

Keyword

Thrombotic microangiopathy; PLASMIC score; Lactate dehydrogenase (LDH)

Figure

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  Fig. 1 Study cohort design outlining the method of patient selection for analysis. The total PLASMIC/ PLASMIC LDH score was calculated with one point designated for each component and subsequently stratified into low risk (0–4 points), intermediate risk (5 points), and high risk (6–7 points).

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  Fig. 2 DeLong’s test for the receiver operator curve (ROC) with a comparison of the area under the curve (AUC) of PLASMIC (black) and PLASMIC-LDH (blue).

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