Interpretability of the Quantra viscoelastic test in patients with haematological malignancies presenting severe thrombocytopenia

Viscoelastic tests have been scarcely evaluated in patients with haematological malignancies and severe thrombocytopenia. The VISCOTHEM-1 study investigated the interpretability of Quantra results in these patients, with platelet count less than 50 × 109/l. The objective was to evaluate the correlation between clot stiffness and platelet contribution to clot stiffness (PCS) measured by Quantra and conventional laboratory platelet counts. In this exploratory, single-centre, nonrandomized prospective cohort (June-December 2024), adults with haematological malignancies, platelet count less than 50 × 109/l and no antiplatelet/anticoagulant therapy or platelet-function disorders were enrolled. Patients underwent a blood count, coagulation assays, Quantra and ROTEM assessments. For patients who received transfusion, a second draw was performed one hour posttransfusion. Forty-six patients were included: 16 with platelet counts less than 10 × 109/l, 15 between 10 and 19 × 109/l, and 15 between 20 and 49 × 109/l. Fourteen patients (31%) experienced bleeding. The median PCS measured by Quantra was 2 hPa [interquartile range (IQR) 2-3.38] and correlated strongly with platelet count using conventional assay (r = 0.84, P < 0.05) and with MCE platelets measured by ROTEM (r = 0.78, P < 0.05). Clot stiffness was moderately correlated with platelet count (r = 0.48, P < 0.05) and strongly with MCF-EXTEM (r = 0.79, P < 0.05). The range of PCS values differentiated most patients except in the less than 10 × 109/l subgroup. The distributions of clot stiffness, clotting time and fibrinogen contribution to clot stiffness measured by Quantra reliably discriminated between all patients regardless of platelet count. After transfusion, PCS and clot stiffness increased significantly. Quantra results were interpretable in patients with haematological malignancies and platelet counts below 50 × 109/l and correlated both with ROTEM parameters and with conventional haemostasis assays.