Risk of thrombosis according to need of phlebotomies in patients with polycythemia vera treated with hydroxyurea

NCCN Guidelines Insights: Myeloproliferative Neoplasms, Version 2.2018

“…In one recent retrospective study, the need for ≥3 phlebotomies per year was associated with a significantly higher rate of thrombosis in patients with PV treated with hydroxyurea (20.5% at 3 years vs 5.3% at 3 years for those receiving ≤2 phlebotomies per year; P<.0001). 47 However, these findings could not be confirmed by other investigators. 48,49 The development of cytopenia (one of the European LeukemiaNet [ELN]-defined criteria for resistance or intolerance to hydroxyurea) at the lowest dose of hydroxyurea is an adverse prognostic factor associated with higher risk of death and transformation to AML.…”

A guideline for the diagnosis and management of polycythaemia vera. A British Society for Haematology Guideline

“…Where frequent venesection is needed to achieve this target then an alternative approach using a cytoreductive agent may need to be considered. High levels of venesection requirement have been reported to have an association with higher thrombosis risk in patients on HC, specifically in those patients requiring 3 or more venesections per year (Alvarez‐Larrán et al , ).…”

No correlation of intensity of phlebotomy regimen with risk of thrombosis in polycythemia vera: evidence from European Collaboration on Low-Dose Aspirin in Polycythemia Vera and Cytoreductive Therapy in Polycythemia Vera clinical trials

“…These results, based on a more powerful analysis of PV patients treated with HU in the settings of controlled prospective trials, do not confirm those recently reported by Alvarez-Larran et al, 10 who showed a correlation between the number of TP and a higher incidence of thrombosis in HU treated patients in an observational cohort. It should be underlined that the median value of HCT in the group treated with 3 or more phlebotomies (46.03%) of the ECLAP study was lower than the median value of hematocrit in the high-HCT arm of the Cyto-PV trial (always above 47.5%), and that this latter value was comparable to the group treated with 3 or more phlebotomies of the Spanish cohort in which higher risk of thrombosis was reported.…”