Management of polycythemia vera to reduce thrombotic events and mortality with phlebotomy and cytoreductive therapy in veterans affairs healthcare system.

Patients with polycythemia vera (PV) have increased incidence of thrombotic events (TEs) that contribute to higher mortality compared to age-matched controls. We aim to compare the impact of phlebotomy (PHL) and cytoreductive therapy (CT) on outcomes in US veterans with PV between Oct 2017 and Dec 2023. PV treatment was categorized into three groups: CT, PHL, and no documented treatment. Among 11,809 veterans with PV, 7151 (60.6%) received CT or PHL treatments. After excluding those with events before or within 90 days of index date (PV diagnosis), we identified 5287 and 5245 qualified patients to examine treatment impact on mortality and TE, respectively. The mortality rate was 15.4% (n = 816), with a median survival time of 4.5, 4.9 or 4.3 years for patients under CT, PHL only, or no treatment, respectively. The TE rate was 9.4% (n = 496), with a median duration (from index date to the first TE or censored date) of 4.2, 4.7, or 4.0 years for patients under CT, PHL, or no treatment, respectively. Both CT and PHL reduced mortality, and there was no significant difference between CT and PHL that lowered the risk of TE. Compared with patients with no documented treatment, patients treated with CT had a 43% lower risk of mortality (HR 0.57, 95% CI 0.45-0.75; p < 0.01), and patients treated with PHL had a 20% lower risk of mortality (HR 0.80, 95% CI 0.65-1.00; p = 0.05). Therefore, in patients with PV, treatment with CT had similar outcome on TE or mortality, compared to those treated with PHL.