Traditional and whole blood coagulative profiles across different variants of COVID-19 acute pneumonia admitted to the Internal Medicine Ward

Purpose: To study COVID-19-associated coagulopathy and the clinical outcomes across different COVID-19 pandemic waves. Methods: We retrospectively analyzed n 344 patients hospitalized for acute COVID-19 to Padova University Hospital between March 2020-March 2023, grouped by variants: Wild-type (G1, n 155; March 2020-January 2021), Alpha (G2, n 79; February-May 2021), Delta (G3, n 50; May-December 2021), and Omicron (G4, n 60; December 2021-March 2023). We compared traditional coagulation tests, thromboelastometry and impedance aggregometry. Clinical outcomes were also considered. Results: Factor VIII decreased progressively from G1 (195%, IQR 149-227) to G4 (156%, IQR 128-197; p < 0.05), as did von Willebrand factor (343%, IQR 244-407 to 235%, IQR 216-247; p < 0.05). Thromboelastometry showed a significantly and progressively: i) prolonged INTEM and EXTEM clot formation time (p < 0.05 in all comparisons); ii) reduced INTEM, EXTEM and FIBTEM maximum clot firmness (p < 0.05 in all comparisons). Platelet aggregation significantly decreased from G1 to G4 (p < 0.05 in all comparisons). VTE occurred in 18.1% of G1 and 19.0% of G2 patients vs. 6.0% and 6.7% in G3 and G4, respectively (p < 0.05 in all comparisons). The 28-day mortality was 15.5% in G1 and 15.2% in G2 vs. 4.0% and 1.7% in G3 and G4, respectively (p < 0.05 in all comparisons). Conclusions: We observed a significant and progressive decrease in hypercoagulability across the four COVID-19 variants. A parallel decline in VTE incidence and 28-day mortality was also observed. Larger studies are needed to ascertain the pathophysiological mechanisms underlying the changes in coagulative profiles and their clinical implications.