Thrombotic burden and longitudinal outcomes in Thai patients with polycythemia vera

BACKGROUND: Polycythemia vera (PV) is a myeloproliferative neoplasm frequently complicated by thromboembolic events. However, data regarding thrombotic burden and long-term outcomes among Asian patients remain limited. MATERIALS AND METHODS: We conducted a retrospective cohort study at a tertiary referral center to evaluate thromboembolic events, treatment-related complications, disease progression, and overall survival in patients with PV. RESULTS: A total of 133 patients were included, with a median age of 61 years (range 18-88). Most patients were male (60.2%). Fifty-one patients (38.3%) experienced at least one thromboembolic event, with 54 events in total, of which 87% occurred before or at PV diagnosis. Arterial thrombosis accounted for 90.7% of all events. Age ≥60 years was significantly associated with thromboembolic events, with an odds ratio of 2.34 (95% confidence interval [CI], 1.07-5.11). After a median follow-up of 7.7 years, the 5-year overall survival was 82.7% (95% CI, 74.61-88.35). Prior thrombosis was associated with an increased risk of death (hazard ratio, 1.98; 95% CI, 1.15-3.42). Hydroxyurea resistance or intolerance occurred in 9.8% of patients. Bleeding complications were observed in 6.8%, including major bleeding in 4.5%. Fibrotic transformation, leukemic transformation, and secondary solid malignancies occurred in 4.5%, 3.8%, and 6.0% of patients, respectively. CONCLUSION: Thromboembolic events were common and predominantly arterial in this Asian PV cohort, occurring mainly before or at diagnosis. Prior thrombosis was associated with inferior survival. Long-term follow-up also revealed disease progression and secondary solid malignancies, underscoring the importance of continued surveillance.