Palpable splenomegaly, older age, and thrombosis history were found to be independent risk factors for thrombosis among patients with post-polycythemia vera (PV) myelofibrosis, according to results of a study published in Thrombosis Research.

PV is a type of Philadelphia chromosome-negative myeloproliferative neoplasm which has elevated thrombosis risk. Post-PV myelofibrosis is a natural progression of PV and although thrombosis is a major cause of death in this population, risk factors have not been identified.

This retrospective study recruited patients at the Second Hospital of Tianjin Medical University and Institute of Hematology and Blood Diseases Hospital in China between October 2000 and October 2020. A cohort of 163 patients with post-PV myelofibrosis and a cohort 163 age- and gender-matched patients with PV that had not progressed to myelofibrosis were assessed for potential thrombosis risk factors.

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Patients with post-PV myelofibrosis and PV were median age 53 years at diagnosis and 50.9% were women.

In the post-PV myelofibrosis cohort, 84 had a thrombotic event. More of the patients with thrombosis were older (P =.023), had palpable splenomegaly (P <.0001), abnormal karyotype (P =.037), hypertension (P =.005), history of cardiovascular events (P =.006), and diabetes (P =.013).

Risk factors for thrombosis events among the post-PV myelofibrosis cohort were palpable splenomegaly (hazard ratio [HR], 3.284; 95% CI, 1.373-7.855; P =.008), prior thrombotic event (HR, 2.767; 95% CI, 1.735-4.412; P <.001), and age 60 years and older (HR, 1.604; 95% CI, 1.004-2.56; P =.048).

Stratified by arterial and venous thrombosis, significant predictors for arterial events included prior thrombotic events and palpable splenomegaly; and for venous events, prior thrombotic events.

Additional study is needed to confirm these findings among an independent cohort of patients.

These data indicated that there were 3 independent predictors for thrombosis risk among patients with post-PV myelofibrosis which may improve thrombosis risk stratification.


Teng G, Zhou Y, Zhang Y, et al. Thrombosis in patients with post-polycythemia vera myelofibrosis: incidence and risk factors. Thromb Res. 2022;212:38-43. doi:10.1016/j.thromres.2022.02.006