Determination of prognosis of Philadelphia chromosome-negative myeloproliferative neoplasms with a simple clinical examination: Retrospective analysis of 71 patients in a single institution.

Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocytosis (ET) and primary myelofibrosis (PMF), are clonal hematopoietic diseases. A single-institution retrospective analysis was performed, including 71 MPN patients diagnosed at the Hakodate Municipal Hospital between April, 2001 and April, 2014, and certain clinical characteristics were identified as effective prognostic factors. The patients were categorized by risk factor scoring based on age, number of abnormal blood cell lineages and splenomegaly at diagnosis, and the association between this categorization and prognosis was analyzed using a statistical procedure. The effect of Janus kinase 2 (JAK2) V617F mutation on prognosis was also investigated. The MPN patients were consolidated into three risk groups based on the margin of intergroup survival differences: i) Score 1-2 (n=23), ii) score 3 (n=24) and iii) score 4-5 (n=24). MPN patients with scores of 4 or 5 exhibited poorer overall survival (OS) compared with those with lower scores (P<0.001). In addition, there were significant differences in event-free survival (EFS) among scoring groups (P=0.0059). PV and ET had a better prognosis compared with PMF, although this analysis suggested that PV and ET patients with scores of 4 or 5 may have a poorer prognosis in terms of OS (P=0.0052) and EFS (P=0.022) and should be closely followed up. We observed no significant prognostic effect of the JAK2V167F mutation for OS (P=0.28) or EFS (P=0.17). Our results suggested that a simple scoring system based on age, blood cell counts and presence of splenomegaly at diagnosis may be used for the long-term prognosis of MPN patients.