Alvarez-Larrán, AlbertoPérez-Encinas, ManuelFerrer-Marín, FranciscaHernández-Boluda, Juan CarlosRamírez, María JoséMartínez-López, JoaquínMagro, ElenaCruz, YasminaMata, María IsabelAragües, PilarFox, María LauraCuevas, BeatrizMontesdeoca, SaraHernández-Rivas, José AngelGarcía-Gutiérrez, ValentínGómez-Casares, María TeresaSteegmann, Juan LuisDurán, María AntoniaGómez, MontseKerguelen, AnaBárez, AbelardoGarcía, Mari CarmenBoqué, ConcepciónRaya, José MaríaMartínez, ClaraAlbors, ManuelGarcía, FrancescBurgaleta, CarmenBesses, CarlosGrupo Español de Neoplasias Mieloproliferativas Filadelfia Negativas2025-01-072025-01-072016-09-29https://hdl.handle.net/10668/25112Hematocrit control below 45% is associated with a lower rate of thrombosis in polycythemia vera. In patients receiving hydroxyurea, this target can be achieved with hydroxyurea alone or with the combination of hydroxyurea plus phlebotomies. However, the clinical implications of phlebotomy requirement under hydroxyurea therapy are unknown. The aim of this study was to evaluate the need for additional phlebotomies during the first five years of hydroxyurea therapy in 533 patients with polycythemia vera. Patients requiring 3 or more phlebotomies per year (n=85, 16%) showed a worse hematocrit control than those requiring 2 or less phlebotomies per year (n=448, 84%). There were no significant differences between the two study groups regarding leukocyte and platelet counts. Patients requiring 3 or more phlebotomies per year received significantly higher doses of hydroxyurea than the remaining patients. A significant higher rate of thrombosis was found in patients treated with hydroxyurea plus 3 or more phlebotomies per year compared to hydroxyurea with 0-2 phlebotomies per year (20.5% vs. 5.3% at 3 years; PenAttribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/AdolescentAdultAgedAged, 80 and overBlood Cell CountCombined Modality TherapyDrug ResistanceFemaleHematocritHumansHydroxyureaMaleMiddle AgedMultivariate AnalysisPhenotypePhlebotomyPolycythemia VeraRegistriesRiskSpainThrombosisTime FactorsTreatment OutcomeYoung Adultresearch article27686377open access10.3324/haematol.2016.1527691592-8721PMC5210240http://www.haematologica.org/content/haematol/102/1/103.full.pdfhttps://pmc.ncbi.nlm.nih.gov/articles/PMC5210240/pdf