From the Guidelines
Polycythemia vera (PV) is diagnosed based on elevated red cell mass, absence of secondary erythrocytosis, and presence of a JAK2 mutation, and is treated with phlebotomy and low-dose aspirin.
Diagnosis
The diagnosis of PV requires the presence of elevated red cell mass, absence of secondary erythrocytosis, and presence of a JAK2 mutation 1. The 2001 WHO criteria for PV include elevated red cell mass, absence of secondary erythrocytosis, splenomegaly, clonal genetic abnormality, and endogenous erythroid colony formation 1. However, the revised criteria propose to replace these with two major criteria: laboratory evidence of increased hemoglobin, hematocrit, or red cell mass, and presence of a JAK2 mutation 1.
Treatment
The treatment of PV aims to reduce the risk of thrombosis and prevent progression to myelofibrosis or acute myeloid leukemia 1. Phlebotomy is the cornerstone of treatment, used to control hematocrit levels and reduce the risk of thrombosis 1. Low-dose aspirin is also used to alleviate microvascular symptoms and prevent thrombosis 1. In high-risk patients, myelosuppressive agents may be used in addition to phlebotomy to prevent thrombosis 1.
Risk Stratification
Risk stratification is important in PV to identify patients at high risk of vascular events 1. Patients with a high risk of thrombosis may require more aggressive treatment, including myelosuppressive agents 1.
Special Considerations
In patients with PV, it is essential to monitor for signs of myelofibrosis or acute myeloid leukemia, and to adjust treatment accordingly 1. Additionally, patients with PV should be cautioned against excessive aspirin use, as it can increase the risk of bleeding 1.
From the Research
Diagnosis of Polycythemia
- Polycythemia may complicate or be the presenting feature of a wide variety of different pathologies 2
- Patients with a raised packed cell volume are divided into those with a raised red cell mass (absolute polycythaemia), and those with a red cell mass within their normal range (apparent polycythaemia) 2
- Erythrocytosis (hemoglobin >16.5 mg/dL in men or >16.0 mg/dL in women) is a required diagnostic criterion for Polycythemia Vera (PV) 3
- More than 95% of patients with PV have a JAK2 gene variant, which helps distinguish PV from secondary causes of erythrocytosis 3
Treatment of Polycythemia
- Early diagnosis and treatment of primary polycythaemia will significantly reduce the morbidity and mortality associated with this condition 2
- Treatment of PV is thus primarily focused on symptom control and survival extension through the prevention of thrombosis and leukemic transformation 4
- All patients with PV should receive therapeutic phlebotomy (goal hematocrit, <45%) and low-dose aspirin (if no contraindications) 3
- Patients who are at higher risk of thrombosis include those aged 60 years or older or with a prior thrombosis, and may benefit from cytoreductive therapy with hydroxyurea or interferon to lower thrombosis risk and decrease symptoms 3
- Ruxolitinib is a Janus kinase inhibitor that can alleviate pruritus and decrease splenomegaly in patients who are intolerant of or resistant to hydroxyurea 3
Management of Cardiovascular Risk
- Patients with PV frequently experience thrombotic events and have elevated cardiovascular risk, including hypertension, dyslipidemias, obesity, and smoking, all of which negatively affect survival 4
- To reduce the risk of thrombotic complications, PV therapy should aim to normalize hemoglobin, hematocrit, and leukocytosis and, in addition, identify and modify cardiovascular risk factors 4
- Current treatment strategies in clinical practice are driven by mitigating the risk of thrombotic events by reducing patients' hematocrit 5