Yi Liu, Fan Lu, Binbin Ji, Wei Song, Hui Shen, Yingjie Xu and Bining Yang.
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Abstract Background: In
the ICU, distinguishing immune mediated thrombotic thrombocytopenic
purpura (iTTP) from sepsis associated thrombotic microangiopathy (TMA)
is time critical. We tested whether serial ADAMTS 13 combined with
targeted coagulation and inflammation markers improves iTTP risk
stratification in a Sepsis 3 ICU cohort and whether a pragmatic rule
out is feasible. |
Introduction
Methods
Study design. We conducted a prospective, single center diagnostic-accuracy study at The Fourth Affiliated Hospital of Soochow University (March 2023–February 2024) focused on Sepsis-3 patients with thrombocytopenia (platelets <100×109/L) and either schistocytes ≥1% or LDH >2× ULN, enrolled ≤24 h. All index tests were prespecified and processed blinded to final adjudication. The study addresses differential diagnosis and risk stratification in Sepsis-3 ICU patients with suspected thrombotic microangiopathy, not all comers with TMA. The protocol conformed to the Declaration of Helsinki and was approved by the ethics committee of the Fourth Affiliated Hospital of Soochow University. All participants provided written informed consent prior to any study procedures.Results
Of 1,274 patients screened, 330 were enrolled within 24 h of ICU admission and completed the index-test schedule, 34 (10.3%) were adjudicated as iTTP, and 296 as non-TTP sepsis-associated TMA/DIC (Figure 1). Baseline profiles showed the anticipated divergence between iTTP and sepsis-associated coagulopathy (Table 1). iTTP patients were younger (mean difference −11 years, 95% CI −17 to −5, p=0.002, FDR q=0.006) and had more severe thrombocytopenia (18 vs 56×109/L, p<0.001, q<0.001), higher LDH (830 vs 610 U/L, p=0.002, q=0.006), and markedly lower ADAMTS-13 activity (7% vs 28%, p<0.001, q<0.001), resulting in a substantially higher VWF:ADAMTS-13 ratio (33 vs 12, p<0.001, q<0.001). Non-TTP patients exhibited the DIC phenotype with higher PT/INR and APTT, lower fibrinogen and AT-III, higher D-dimer, and higher ISTH-DIC and SIC scores (all p<0.001, q<0.001), consistent with consumption coagulopathy. Heparin exposure by anti-Xa categories was more frequent in non-TTP, while LA prevalence was identical (8.8%, p=0.999).![]() |
Figure 1. Screening,
eligibility, and analysis populations. Of 1,274 patients screened, 330
were included ≤24 h (iTTP = 34; non‑TTP = 296). |
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Table 1. Baseline characteristics by final diagnosis. |
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Table 2. Diagnostic model performance. |
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Discussion
In this Sepsis-3 ICU cohort with TMA features, moving from a single baseline ADAMTS-13 measure to dynamic profiling produced a substantial gain in iTTP discrimination, with incremental improvements after adding a parsimonious coagulation index and a two-analyte inflammation index, while maintaining calibration and net benefit. The pragmatic rule-out achieved 97.1% sensitivity and 99.6% NPV in the care-embedded analysis, and an RCV-anchored threshold (≥ 35% or ≥ 10%, points) preserved 100% sensitivity/NPV at the expected cost to specificity, supporting a safety first option when the consequences of missed iTTP are high. A 72-h high-risk phenotype was associated with higher 28-day mortality and greater SOFA worsening, underscoring the biological plausibility that early enzymatic and endothelial-inflammatory signals capture clinically meaningful risk.Ethics approval and consent to participate
The protocol conformed to the Declaration of Helsinki and was approved by the ethics committee of the Fourth Affiliated Hospital of Soochow University. All participants provided written informed consent prior to any study procedures.Data availability statement
Data sets generated during the current study are available from the corresponding author on reasonable request.Author Contribution Statement
The authors confirm contribution to the paper as follows: study conception and design: B.Y.; data collection: Y.L., F.L., B.J., W.S., H.S., Y.X.; analysis and interpretation of results: Y.L., F.L., B.J., W.S., H.S., Y.X.; draft manuscript preparation: Y.L., F.L., B.J., W.S., H.S., Y.X., B.Y. All authors reviewed the results and approved the final version of the manuscript.References