Using prospective clinical data from the REVEAL study, researchers analyzed the potential association between thrombotic events (TEs) and white blood cell count among patients with polycythemia vera. The analysis involved 2,271 patients with polycythemia vera with a median follow-up of 44.7 (range 2-59) months. Aaron T. Gerds, MD, MS, and his team identified 142 TEs in 106 patients. Initial TE occurrence was significantly associated with two measures: hematocrit greater than 45% (HR=1.84; 95% CI, 1.234-2.749; P=0.0028) and white blood cell count greater than 11×109/L (HR=2.35; 95% CI, 1.598-3.465; P<0.001). In cases where hematocrit was controlled at 45% or less, white blood cell count greater than 12×109/L was significantly associated with TE occurrence. Researchers noted that the relationship between elevated white blood cell count and initial TE occurrence was significant for both low-risk and high-risk polycythemia vera. Given their findings, Dr. Gerds and coauthors recommended incorporating white blood cell count into risk stratification.
