Thrombosis among 1537 patients with JAK2V617F‐mutated myeloproliferative neoplasms: Risk factors and development of a predictive model

To explore the risk factors of thrombosis in patients with JAK2(V617F) -mutated myeloproliferative neoplasms (MPNs), a cohort of 1537 Chinese patients with JAK2(V617F) -mutated MPN was retrospectively analyzed. The Kaplan-Meier method and multivariate Cox analysis were used to study the risk factors of thrombosis in patients with JAK2(V617F) -mutated MPN. Among the 1537 MPN patients, 931, 468, and 138 had polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), respectively. The median follow-up time was 7 years (range 1-47), and 12.8% of patients (197/1537) died during this period. A total of 16.8% (259/1399) of PV and ET patients had secondary myelofibrosis, and 2.5% (38/1537) of patients developed acute myeloid leukemia (AML). Thrombotic events occurred in 43.9% (675/1537) of patients, among which 91.4% (617/675) were arterial thrombosis and 16.6% (112/675) were venous thrombosis. The number of thrombotic events in PV, ET, and PMF patients was 439 (47.2%), 197 (42.1%) and 39 (28.2%), respectively. The multivariate analysis indicated that age >/=60 years old, HCT >/=48%, at least one cardiovascular risk factor, a history of thrombosis, and JAK2(V617F) allele burden (V617F%) >/=50% are risk factors for thrombosis in JAK2(V617F) -mutated MPN. According to the results of the multivariate analysis, a risk model of thrombosis was established and comprised low-risk (0 points), intermediate-risk (1 points) and high-risk (>/=2 points) groups, among which the incidence of thrombosis was 9.1%, 33.7% and 72.9%. For elderly patients with JAK2(V617F) -mutated MPN and a history of thrombosis, reducing the V617F%, controlling HCT and preventing cardiovascular risk factors are necessary measures to prevent thrombosis.