Improving the PLASMIC score with the use of RDW-SD in the differential diagnosis for thrombotic thrombocytopenic purpura in Chinese patients

Abstract

Background

This study aimed to identify laboratory parameters that could optimize the PLASMIC score, thereby improving its diagnostic accuracy for thrombotic thrombocytopenic purpura (TTP).

Methods

We performed a retrospective analysis of 136 patients with suspected TTP who had available ADAMTS-13 activity measurements. Patients were stratified into two groups based on ADAMTS-13 activity: a TTP group (n = 49) and a non-TTP group (n = 87). Routine laboratory parameters—including hemoglobin (HGB), red blood cell distribution width-standard deviation (RDW-SD), mean corpuscular volume (MCV), platelet count (PLT), alanine aminotransferase (ALT), aspartate aminotransferase (AST), direct bilirubin (DBIL), indirect bilirubin (IBIL), lactate dehydrogenase (LDH), creatinine (CR), urea (UREA), international normalized ratio (INR), and D-dimer—were compared between groups. Statistically significant parameters were selected as candidate variables to refine the PLASMIC score. The diagnostic performance of the modified model was evaluated using receiver operating characteristic (ROC) curve analysis.

Results

Six parameters—HGB, PLT, ALT, RDW-SD, IBIL, and LDH—demonstrated significant differences between TTP and non-TTP patients. Multivariate logistic regression identified RDW-SD, PLT, and LDH as independent predictors of TTP. Based on these findings, we revised the PLASMIC score by substituting MCV with RDW-SD. The modified model exhibited a higher area under the curve (AUC) (0.907 vs 0.817) while maintaining sensitivity (95.9%) and improving specificity (70.1% vs 65.9%) compared to the original.

Conclusion

The modified PLASMIC score model may improve diagnostic accuracy for TTP in similar patient populations, but requires external validation in diverse cohorts to confirm its broader utility.

Graphical Abstract

Keywords

Thrombotic thrombocytopenic purpura laboratory test platelet RDW-SD lactate dehydrogenase diagnostic model

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References

Mariotte

Azoulay

Galicier

, et al. Epidemiology and pathophysiology of adulthood-onset thrombotic microangiopathy with severe ADAMTS13 deficiency (thrombotic thrombocytopenic purpura): a cross-sectional analysis of the French national registry for thrombotic microangiopathy. Lancet Haematol 2016; 3: e237–e245.

Mannucci

. Understanding organ dysfunction in thrombotic thrombocytopenic purpura. Intensive Care Med 2015; 41: 715–718.

Azoulay

Bauer

Mariotte

, et al. Correction to: expert statement on the ICU management of patients with thrombotic thrombocytopenic purpura. Intensive Care Med 2020; 46: 570–571.

Zheng

Al-Housni

Cataland

, et al. International society on thrombosis and haemostasis. 2025 focused update of the 2020 ISTH guidelines for management of thrombotic thrombocytopenic purpura. J Thromb Haemostasis 2025; 17: 360–365.

Veyradier

. Von Willebrand Factor--A New Target for TTP Treatment? N Engl J Med 2016; 374: 583–585.

Scully

Cataland

Peyvandi

, et al. Caplacizumab treatment for acquired thrombotic thrombocytopenic purpura. N Engl J Med 2019; 380: 335–346.

Amorosi

Ultmann

. Thrombotic thrombocytopenic purpura: report of 16 cases and review of the literature. Medicine 1966; 45: 139–160.

Rock

Shumak

Buskard

, et al. Comparison of plasma exchange with plasma infusion in the treatment of thrombotic thrombocytopenic purpura. Canadian apheresis study group. N Engl J Med 1991; 325: 393–397.

Joly

Coppo

Veyradier

. Thrombotic thrombocytopenic purpura. Blood 2017; 129: 2836–2846.

10.

Bendapudi

Hurwitz

Fry

, et al. Derivation and external validation of the PLASMIC score for rapid assessment of adults with thrombotic microangiopathies: a cohort study. Lancet Haematol 2017; 4: e157–e164.

11.

Tang

Wang

, et al. Validation of the PLASMIC score, a clinical prediction tool for thrombotic thrombocytopenic purpura diagnosis, in Chinese patients. Thromb Res 2018; 172: 9–13.

12.

Lee

Lin

Kang

, et al. A validation and modification of PLASMIC score by adjusting the criteria of mean corpuscular volume and international normalized ratio. J Clin Apher 2023; 38(5): 582–589. DOI: 10.1002/jca.22068, Epub 2023 Jun 16.

13.

Reddy

Newsom

Sakurai

, et al. Performance of the PLASMIC score is improved with a positive score defined as ≥5 and with the inclusion of neurological symptoms. Br J Haematol 2022; 198(1): e1–e3. DOI: 10.1111/bjh.18123, Epub 2022 Mar 8.

14.

Zhao

Zhou

, et al. A modified PLASMIC score including the lactate dehydrogenase/the upper limit of normal ratio more accurately identifies Chinese thrombotic thrombocytopenic purpura patients than the original PLASMIC score. J Clin Apher 2020; 35: 79–85.

15.

Khalighi

, et al. External validation of the PLASMIC score: a clinical prediction tool for thrombotic thrombocytopenic purpura diagnosis and treatment. J Thromb Haemostasis 2018; 16: 164–169.

16.

Keiser

Boyd

Rehberg

, et al. A high LDH to AST ratio helps to differentiate pregnancy-associated thrombotic thrombocytopenic purpura (TTP) from HELLP syndrome. J Matern Fetal Neonatal Med 2012; 25: 1059–1063.

17.

George

Nester

. Syndromes of thrombotic microangiopathy. N Engl J Med 2014; 371: 654–666.

18.

Zafrani

Mariotte

Darmon

, et al. Acute renal failure is prevalent in patients with thrombotic thrombocytopenic purpura associated with low plasma ADAMTS13 activity. J Thromb Haemostasis 2015; 13: 380–389.

19.

Salvagno

Sanchis-Gomar

Picanza

, et al. Red blood cell distribution width: a simple parameter with multiple clinical applications. Crit Rev Clin Lab Sci 2015; 52: 86–105.

20.

Zhang

Zhao

. Red blood cell distribution width as a prognostic biomarker for mortality in traumatic brain injury. Int J Clin Exp Med 2015; 8: 19172–19175.

21.

Mohindra

Mishra

Mathew

, et al. Red cell distribution width (RDW) index as a predictor of severity of acute ischemic stroke: a correlation study. Adv J Emerg Med 2019; 4: e24.

22.

Zhang

Tian

, et al. Diagnostic value of joint detection of homocysteine and RDW CV on acute myocardial infarction. Eur Rev Med Pharmacol Sci 2017; 21: 4472.

23.

Karabulut

Arcagok

. New diagnostic possibilities for early onset neonatal sepsis: red cell distribution width to platelet ratio. Fetal Pediatr Pathol 2020; 39: 297–306.

24.

Nagajothi

Braverman

. Elevated red cell distribution width in the diagnosis of thrombotic thrombocytopenic purpura in patients presenting with anemia and thrombocytopenia. South Med J 2007; 100: 257–259.

25.

Fei

Wang

Zhang

, et al. Reference intervals of systemic immune-inflammation index, neutrophil to lymphocyte ratio, platelet to lymphocyte ratio, mean platelet volume to platelet ratio, mean platelet volume and red blood cell distribution width-standard deviation in healthy Han adults in Wuhan region in central China. Scand J Clin Lab Invest 2020; 80: 500–507.

26.

Hoffmann

Nabbe

van den Broek

. Effect of age and gender on reference intervals of red blood cell distribution width (RDW) and mean red cell volume (MCV). Clin Chem Lab Med 2015; 53: 2015–2019.