Hematocrit Control ‘Suboptimal’ in More Than Half of Patients with Polycythemia Vera

By Cecilia Brown - Last Updated: February 2, 2023

Hematocrit control was “suboptimal” in more than half of patients with high-risk polycythemia vera, and in nearly two-thirds of low-risk patients, according to a retrospective study.

Srdan Verstovsek, MD, of the MD Anderson Cancer Center, and colleagues conducted the research and published their findings in Annals of Hematology.

Polycythemia vera is associated with an increased risk of thrombotic events and death. Targeted therapeutic interventions, phlebotomy, and cytoreduction medications are used to maintain hematocrit levels below 45% and prevent adverse outcomes.

Dr. Verstovsek and colleagues examined medical and pharmacy claims from 28,306 patients who began polycythemia vera treatment between 2011 and 2019. All patients had at least two polycythemia vera diagnosis codes, at least one year of polycythemia vera treatment history, and at least one prescription claim and medical claim in 2018 and 2019. The researchers designated the 4,246 patients with at least two hematocrit test results in linked outpatient laboratory data as the hematocrit group. Dr. Verstovsek and colleagues also characterized patients as high risk (n=3,920) or low risk (n=629) based on age and prior thrombotic history when treatment began.

Nearly all (83%) low-risk patients started treatment with phlebotomy monotherapy, while 60% of high-risk patients began with phlebotomy monotherapy. Most low-risk patients (81%) continued their original therapy at a median follow-up of 808 days, while 74% of high-risk patients continued their original therapy.

More than half of high-risk patients who started treatment with phlebotomy monotherapy sometimes or always had hematocrit levels above 50%, while 64% of low-risk patients sometimes or always had hematocrit levels above 50%.

“Hematocrit control was suboptimal in both risk groups,” Dr. Verstovsek and colleagues wrote.

At least one thrombotic event occurred after treatment began in 20% of high-risk patients, 8% of low-risk patients, and in 16% of all patients studied.

“This real-world study suggests that currently available [polycythemia vera] treatments may not be used to full advantage,” Dr. Verstovsek and colleagues concluded.


Verstovsek S, Pemmaraju N, Reaven NL, et al. Real-world treatments and thrombotic events in polycythemia vera patients in the USA. Ann Hematol. 2023. doi:10.1007/s00277-023-05089-6

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