Leukocytosis in polycythemia vera and splenomegaly in essential thrombocythemia are independent risk factors for hemorrhage

Background: Long-term outcomes are favorable for patients with polycythemia vera (PV) and for patients with essential thrombocythemia (ET). However, hemorrhage is a significant cause of morbidity and mortality in those patients. Methods: We retrospectively recruited 247 patients who had received a diagnosis of PV (n = 101) or ET (n = 146) during the period 2001-2010. Results: After a median follow-up period of 36.2 months, the cumulative incidence of hemorrhage was 39.6% in patients with PV (6.2% per person-year) and 29.7% in patients with ET (5.9% person-years). Episodes of major bleeding occurred in 9.9% of patients with PV and in 14.4% of patients with ET. Overall survival was significantly shorter among patients with hemorrhage than among those without said complication (P < 0.001 for overall patients; P = 0.002 for patients with PV; P = 0.026 for patients with ET). In the univariate analysis, age ≥60 yr (OR: 4.77, P = 0.046) and WBC ≥ 16 × 10⁹/L (OR: 4.15, P = 0.010) were predictors of hemorrhage in patients with PV, and age ≥60 yr (OR: 3.25, P = 0.040), WBC ≥ 16 × 10⁹/L (OR: 2.89, P = 0.024), albumin <4.0 g/dL (OR: 4.10, P = 0.002), and splenomegaly (OR: 5.19, P = 0.002) were predictors of hemorrhage in patients with ET. Multivariate analysis showed that WBC ≥ 16 × 10⁹/L was the only significant risk factor for hemorrhage in patients with PV (OR: 3.51, P = 0.026) and that splenomegaly was the only risk factor for hemorrhage in patients with ET (OR: 3.00, P = 0.048). Conclusion: Leukocytosis in PV and splenomegaly in ET are independent risk factors for hemorrhage.