OC 03.1 - Risk Factors Associated with Thrombosis at Presentation of Polycythemia Vera (PV)

Background: Polycythemia vera (PV), a myeloproliferative neoplasm, typically manifests with thromboembolism and can lead to morbidity or death. However, risk factors for thrombosis in PV vary across different studies.

Aims: To evaluate risk factors for thrombosis at the presentation of PV and to investigate thrombosis following PV diagnosis, thrombosis-free survival, and overall survival.

Methods: A retrospective study was conducted. The ICD-10 was searched, and medical records of the patients were reviewed from January 2000 to November 2023. Patients diagnosed with PV according to the WHO 2022 criteria were included. Baseline characteristics and laboratory data at the time of diagnosis were collected. The incidence of thrombosis (both symptomatic and incidental findings) after the diagnosis of PV, as well as the rates of transformation to myelofibrosis or acute leukemia, was assessed. Survival analyses of the patients were performed, stratified by ELN-risk stratification.

Results: A total of 192 patients were enrolled, and 24.5% experienced thrombosis at presentation. Arterial thrombosis comprised 89.4%, with ischemic stroke being the most common type. The mean age at diagnosis was 60.47±14.18 years, with 53.65% aged ≥60 years. Males constituted 73.96% of the cohort. The median follow-up duration was 2.82 years (IQR:0.76-6.62). Hypertension (75%) was the most prevalent underlying disease. Almost all patients (91.67%) had JAK2 V617F mutation. Intriguingly, none of the parameters (age, cardiovascular risk factors, hemoglobin, white blood cell counts, platelet counts, or prior thrombosis) were associated with thrombosis at presentation. Only 3.13% had thrombosis during follow-up. The 10-year cumulative incidences of transformation to myelofibrosis and acute leukemia were 17.45% and 4.91%, respectively. While ELN-risk stratification failed to discriminate thrombosis-free survival between the low and high-risk groups, it remained effective in predicting the overall survival of PV patients.

Conclusion(s): No single parameter is associated with thrombosis at the presentation of PV. ELN-risk stratification remains a valuable tool for predicting overall survival.