Platelet count rose while D-dimer levels dropped as deaths and thrombosis declined, an observational study on anticoagulation shift in COVID-19.

Sjöström, Anna; Wersäll, Johanna; Warnqvist, Anna; Farm, Maria; Magnusson, Maria; Oldner, Anders; Ågren, Anna; Antovic, Jovan P; Bruzelius, Maria

BACKGROUND High levels of D-dimer and low platelet counts are associated with poor outcome in COVID-19. As anticoagulation appeared to improve survival, hospital-wide recommendations regarding higher doses of anticoagulation was implemented 4/9/2020. OBJECTIVES To investigate if trends in D-dimer levels and platelet counts associated with death, thrombosis, and the shift in anticoagulation. METHODS Retrospective cohort study of 429 patients with COVID-19 at Karolinska University Hospital. Information on D-dimer levels and platelet counts was obtained from laboratory databases and clinical data from medical records. RESULTS Thirty-day mortality and thrombosis rate was 19% and 18%, respectively. Pulmonary embolism was common; 65/83 (78%). Increased D-dimer levels the first week in hospital were significantly associated with death and thrombosis (OR 6.06; 95% Cl 2.10-17.5, and 3.11; 95% CI 1.20-8.10, respectively). If platelet count increased more than 35×109/L per day, the mortality and thrombotic risk decreased (OR 0.16; 95% CI 0.06-0.41, and OR 0.36; 95% CI 0.17-0.80). After implementation of updated hospital-wide recommendations, the daily mean significantly decreased regarding D-dimer levels while platelet counts rose; -1.93; 95% CI -1.00-2.87 mg/L FEU and 65; 95% CI 54-76 ×109/L and significant risk reductions for death and thrombosis were observed; OR 0.48; 95% CI 0.25-0.92 and 0.35; 95% CI 0.17-0.72. CONCLUSIONS In contrast to D-dimer levels, increase of platelet count over the first week in-hospital was associated with improved survival and reduced thrombotic risk. The daily mean levels of D-dimer dropped while the platelet counts rose, coinciding with increased anticoagulation and a decline in thrombotic burden and mortality.