Incidence and Characteristics of Polycythemia Vera, Essential Thrombocythemia and Primary Myelofibrosis in Thailand: A 5-Year Retrospective Study

Background: Polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF) are members of myeloproliferative neoplasm group. They shared common features such as JAK2 V617F+ mutation, thrombosisor hemorrhage, progression to marrow fibrosis or acute leukemia.

Objective: To study incidence and clinical characteristics of PV, ET and PMF with complications and treatment modalities in Thailand.

Study Designs: Retrospective chart review

Methods: All JAK2 V617F+ and V617F- mutation patients during 2008-2012 were reviewed for demographic data, diagnosis of PV, ET and PMF according to WHO 2008 criteria, complications and treatment.

Results: 363 of 735 patients were 140 PV, 172 ET, 47 PMF and 4 MPN-U. 372 patients were excluded due to routine thrombotic workup (98), secondary erythrocytosis (97), reactive thrombocytosis (55), CML (26), HES/eosinophilia (24), MPN/MDS (3), others (69). In PV, JAK2 V617F+ and JAK2 exon 12 mutation patients were 106 and 2. PV showed male:female ratio of 85:55, mean age 57.7 year (11-86), mean hemoglobin 17.6 g/dl (6.7-24.6), and received aspirin (125), hydroxyurea (116), phlebotomy (84), clopidogrel (10), warfarin (7), anagrelide (6), busulfan (5) and each for interferon, oxymethalone, corticosteroid, and JAK inhibitor. Thrombosis:hemorrhage was 34:16. Myelofibrosis and AML transformation were 7 and 2. In ET, JAK2 V617F+ patients were 121. ET showed male:female ratio of 83:89, mean age 59.45 year (14-91), mean platelet count 924,168/mm³ (283,000-2,235,000), and received aspirin (140), hydroxyurea (139), anagrelide (47), warfarin (11), clopidogrel (7), erythropoietin (6), oxymethalone (3), busulfan (3), corticosteroid (2), interferon (1) and splenectomy (1). Thrombosis:hemorrhage was 52:16. Myelofibrosis and AML transformation were 4 and 1. In PMF, JAK2 V617F+ patients were 32. PMF showed male:female ratio of 21:26, mean age 62.2 year (23-81), mean hemoglobin 8.6 g/dl (3.7-15.5), mean subcostal splenic size 10 cm (1-26) and received hydroxyurea (26), erythropoietin (16), corticosteroid (10), oxymethalone (8), JAK inhibitor (7), transfusion dependency (6), aspirin (3), warfarin (2) and each for anagrelide, thalidomide, splenectomy and allogeneic transplantation. Thrombosis:hemorrhage was 4:5. AML transformation was 4. In multivariate analysis, previous thrombosis, clopidogrel use, splenomegaly, alcohol use and JAK2 V617F+ were independent risk factors for thrombosis.

Conclusion: PV, ET and PMF carry high risk for vascular events.