Thrombotic Events and Risk Factors for Thrombosis in Polycythemia in Senegal, West Africa

Objectives: We aim to identify thrombotic events and risk factors for thrombosis (RFT) comparing polycythemia vera (PV) and secondary polycythemia (SP) patients. Methods: We carried out a retrospective study of a cohort of 59 patients with PV (n=34) and SP (n=25) followed for a period of 14 years. Variables studied were the frequency and type of thrombosis, sociodemographic, clinical, and biological RFT. Statistical analysis was performed using SPSS software version 18. Multivariate analysis was performed to identify RFT. Results: Mean age in PV was 53 years (33 - 79) and 44.5 years (5 - 78) in SP (p=0.74). The sex ratio in PV was 1.12 and 2.57 in PS (p=0.52). Sixteen patients had thrombotic events (27.1%) including 12 PV (35.3%) versus 4 SP (16%) (p=0.09). Twenty-two thrombotic events were identified; 14 (63.7%) of arterial thrombosis and 8 (36.3%) of venous thrombosis. There were 18 thrombotic events (81.8%) in PV versus 4 (18.2%) in SP (p=0.02). Arterial thrombosis was more frequent in PV (55.6%). Thrombosis events were more frequent in female patients (59.1%). RFT in PV were age (40-59 years), hematocrit >45% and thrombocytosis ≥ 600 G/L and in SP, RFT were hematocrit >45% and hypercholesterolemia. After multivariate analysis, hematocrit >45% was the only RFT independently associated with thrombosis occurrence. Conclusion: We show through this study, a frequent occurrence of arterial thrombosis in polycythemia. Main RFT is the high hematocrit level (>45%). We insist on the interest of therapeutic bloodletting, sometimes associated with cytoreductive treatment in order to maintain a hematocrit level <45%.