Long-term real-world thrombotic and clinical outcomes in polycythemia vera - a hospital-based i2b2 cohort study.

Though the thrombotic risk in polycythemia vera (PV) is well known, long-term real-world data remain limited. This retrospective study at Bern University Hospital aimed to evaluate complications in PV patients, focusing on thrombotic events, associated risk factors, and disease outcomes. Among 727,731 screened adults, 107 PV patients were identified (median age 58 years, range 18–92; 51% male). Median follow-up was 115 months (range 1–353). Thrombotic events occurred in 56% of patients, including 58% arterial and 42% venous events. Arterial and venous thrombosis before or at diagnosis was documented in 9 (8.4%) and 36 (33.6%) patients, respectively, and in 13 (12.1%) during follow-up. Splanchnic thrombosis was associated with younger age and splenomegaly. Multivariate analysis showed an increased thrombotic risk linked to dyslipidemia (RR 2.573, 95% CI 1.058–6.257) and older age at diagnosis (> 60 years; RR 2.524, 95% CI 1.111–5.734). Risk of death increased with age (RR 1.052, 95% CI 1.009–1.097) and myelofibrosis transformation (RR 6.856, 95% CI 1.948–24.120). This long-term study confirms a high thrombotic burden in PV, especially arterial events. Splanchnic thrombosis typically presented early on in younger patients without recurrence. The high prevalence of cardiovascular risk factors highlights the critical importance of managing these risks to mitigate thrombotic complications in PV.