Influence of Blood Count, Cardiovascular Risks, Inherited Thrombophilia, and JAK2 V617F Burden Allele on Type of Thrombosis in Patients With Philadelphia Chromosome Negative Myeloproliferative Neoplasms.

INTRODUCTION: Thrombosis is the most common complication in Philadelphia chromosome negative (Ph-) myeloproliferative neoplasms patients.

PATIENTS AND METHODS: In a cohort of 258 Ph- myeloproliferative neoplasm patients, the difference between patients with and without thrombosis was analyzed according to genetic thrombophilia factors, JAK2 V617F status and burden allele, blood count, cardiovascular risk factors and age. Patients were also divided in polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) subgroups as well as by the type of thrombosis.

RESULTS: Analysis of cardiovascular risk factors regarding arterial thrombosis showed that PV patients with thrombosis had higher incidence of diabetes (P = .030), ET patients more often had hypertension (P = .003) and hyperlipidemia (P = .005), while PMF patients had hyperlipidemia (P = .046) and at least one cardiovascular risk factor (P = .044). Moreover, leukocytes > 18 × 109 /L and V617F burden allele > 25.7% were statistically significantly different in PV patients (P = .019 and borderline significant at P = .055, respectively), while in ET patients leukocytes > 9.2 × 109 /L (P < .001) and age at diagnosis of > 55 years were statistically significantly different (P = .002). PMF patients with V617F burden allele ≤ 34.8% were more prone to thrombosis (P = .032). When comparing patients with and without venous thrombosis, cutoff value of V617F burden allele > 90.4% was significant for PV patients with thrombosis (P = .036), as was > 56.7% for PMF patients with thrombosis (P = .046). Platelets ≤ 536 × 109 /L and age at diagnosis > 54 years showed statistically significant difference for ET patients with thrombosis (P = .015 and P = .041, respectively).

CONCLUSION: On the basis of our results, a new scoring system for thrombosis risk in PV could be made, while PMF prognostic model may be expanded for better recognition of potential thrombotic risk factors.