Incidence of thrombosis and bleeding in patients with JAK2- positive myeloproliferative neoplasms receiving low-dose aspirin: a systematic review and meta-analysis
In brief
Low-dose aspirin was linked to 40% fewer clots but 2.5-fold more bleeding
Across 10 studies of JAK2-positive myeloproliferative neoplasms, thrombosis rates were 40% lower with low-dose aspirin, while bleeding rates were about 2.5 times higher. The findings suggest a tradeoff, but confidence in the evidence was low, so the balance of benefit and harm for individual patients remains uncertain.
- Journal
- Journal of thrombosis and haemostasis : JTH (Q1)
- Published
- 17 October 2026
- Study design
- Systematic review of cohort studies
- Evidence level
- Level 4, Very Low (CEBM 4)
- Authors
- Kristina Vrotniakaite-Bajerciene, Caterina E Marx, Tobias Tritschler, Risa Shorr, Marc Carrier, Dean A Fergusson, et al.
- PMID
- 42892330
- DOI
- 10.1016/j.jtha.2026.09.044
Why clinicians should know about it
- Picked for Hematology (paper of the day, 23 October 2026): Aspirin reduces thrombosis, increases bleeding in JAK2 MPN
Abstract
BACKGROUND: Patients with JAK2V617F-positive myeloproliferative neoplasms (MPNs) are at increased thrombotic risk and commonly receive low-dose aspirin, yet its net clinical benefit is uncertain. OBJECTIVES: We estimated the incidence of thrombotic and bleeding events in patients with JAK2-positive MPNs treated with low-dose aspirin. METHODS: A systematic review was performed for studies evaluating thrombotic and hemorrhagic events in patients with JAK2V617F-positive MPNs while taking low-dose aspirin. Study-level incidence rates (IR) per 100 person-years (PY) and incidence rate ratios (IRR) comparing aspirin use versus no aspirin were calculated and pooled using random-effects meta-analysis. The certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. RESULTS: We included 3 randomized clinical trials and 7 observational studies (n=1,760 with aspirin, n=367 without aspirin). The pooled IR of thrombotic events in JAK2V617F-positive MPN patients receiving low-dose aspirin prophylaxis was 2.72 per 100 PY (95% confidence interval (CI) 1.59 - 4.65; I2=93%) with pooled IRR receiving aspirin versus no aspirin of 0.59 (95% CI 0.40 - 0.86, I2=16%). The pooled IR of major and non-major bleeding on low-dose aspirin prophylaxis was 1.97 (95% CI 1.06 - 3.65; I2=90%) per 100 PY with pooled IRR of 2.43 (95% CI 1.15 - 5.11; I2=43%). The GRADE level of confidence for the investigated risks was low. CONCLUSIONS: Aspirin was associated with a 40% reduction in thrombosis but a 2.5-fold increase in bleeding risk with low certainty of evidence. More studies are needed to gain high-quality evidence the better define the role of aspirin in JAK2V617F-positive MPNs.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.