Effect of low-dose warfarin on D-dimer levels during sickle cell vaso-occlusive crisis: a brief report

Objective: To evaluate the activation of clotting systems in patients with sickle cell disease (SCD) by measuring the plasma D-dimer level and to determine the effect of low-dose warfarin on D-dimer level during vaso-occlusive crisis.<LF>Methods: Plasma D-dimer level was measured in 65 blood samples of 37 adult patients with SCD who were hospitalized for vaso-occlusive painful crisis. D-dimer level of patients who were on low-dose warfarin was compared with those patients who were not on any anticoagulation treatment. Analysis of variance (ANOVA) was carried out to determine factors significantly associated with low D-dimer level in patients with SCD. The following factors were included in the ANOVA model; warfarin, homozygous hemoglobin S, history of blood transfusion in past 3 months, hydroxyurea, hemoglobin S%, hemoglobin F%, white blood cell counts, hemoglobin level, platelet count, and plasma fibrinogen level. Results: Overall median D-dimer level in 65 samples was 2.7 mug fibrinogen equivalent units (FEU)/mL (0.34-4). Patients who were on low-dose warfarin had a median D-dimer level of 0.81 mug FEU/mL (0.34-1.8) compared with 3.1 mug FEU/mL (0.94-4) in those patients who were not on anticoagulation treatment. Using ANOVA to model D-dimer levels, only warfarin was significantly correlated with low D-dimer levels after controlling for other variables. Conclusions: Patients with SCD during vaso-occulsive painful crisis have an elevated D-dimer level. Low-dose anticoagulation treatment is associated with a significant reduction in the D-dimer levels.