Background: Arterial (3-fold) and venous (10-fold) thromboembolism are more common in myeloproliferative neoplasm (MPN) than general population with rates as high as 50% in polycythemia vera (PV) and essential thrombocythemia (ET).1,2 While primary prophylaxis with aspirin is not debated for prevention of arterial and venous thromboembolism, the choice of anticoagulant for secondary prophylaxis and treatment for VTE is unclear. Hence, we aim to study the use of direct oral anticoagulants (DOACs) for treatment of thromboembolism in MPN patients from the existing literature and meta-analyze them.

Methods: We searched online databases for articles that reported the incidence of primary efficacy and safety outcomes while using DOACs (apixaban, rivaroxaban, edoxaban and dabigatran) in patients with MPNs up to January 2021. Primary efficacy outcome was defined as incidence of recurrent thrombosis and primary safety outcome was defined as rates of major bleeding. Analysis was done using R (R Core Team, 2020) and cumulative incidence rate with 95 % confidence interval was used as summary

Results: Six studies were included for this analysis.3–8 The cumulative incidence rate of thrombosis while on DOACs came out to be 3 per 100 patient years (with 95% CI ranging from 1 to 4 per 100 patient years, I2=65.88%). (Figure 1) Similarly, the primary safety outcome was 2 per 100 patient years (with 95% CI ranging from 1 to 4 per 100 patient years, I2=65.13%). (Figure 2)

Conclusions: Our meta-analysis shows relatively low incidence of recurrent thrombosis and major bleeding rates while on DOACs compared to historical cohort as the rates of recurrent thrombosis while on vitamin K antagonist is reported to be 4.5 to 4.7 per 100 patient years. 9,10 Use of DOACs is approved and commonly used in cancer patients with VTE11 but many of these randomized trials excluded MPN patients. Hence, our study supports the use of DOACs in this population until larger randomized trials comparing DOACs directly to other anticoagulants in MPN patients are available.

IMAGE 1: Figure 1: Forest plot summarizing Incidence Rates of thrombosis

IMAGE 2: Figure 2: Forest plot summarizing Incidence rates of hemorrhage