Polycythemia Vera: Rapid Evidence Review

Polycythemia vera is one of three stem-cell-derived myeloid malignancies commonly known as myeloproliferative neoplasms. It is characterized by erythrocytosis, often with associated leukocytosis and thrombocytosis. It has a significant negative impact on overall mortality and morbidity in the form of arterial and venous clots, symptoms of fatigue and pruritus, and conversion to leukemia and myelofibrosis. The World Health Organization's major diagnostic criteria include an elevated hemoglobin or hematocrit level, abnormal results on bone marrow biopsy, and presence of the Janus kinase 2 genetic mutation, which is present in approximately 98% of cases. The only minor criterion is a subnormal erythropoietin level, which helps differentiate polycythemia vera from common causes of secondary erythrocytosis such as smoking, sleep apnea, and testosterone use. First-line treatments, such as low-dose aspirin and goal-directed phlebotomy to a hematocrit level of less than 45% to reduce thrombotic events, improve quality of life and prolong survival. When indicated, cytoreductive therapy, primarily with hydroxyurea, can be added with consideration of second-line agents such as pegylated interferon-alfa, busulfan, and ruxolitinib, depending on the clinical scenario. Smoking cessation and cardiometabolic disease are modifiable risk factors that should be addressed to reduce the risk of thrombosis. Currently, no medications have been shown to cure the disease or to reduce the risk of conversion to leukemia and myelofibrosis.