Dynamic Model for Predicting Death Within 12 Months in Patients With Primary or Post–Polycythemia Vera/Essential Thrombocythemia Myelofibrosis

PURPOSE: Current prognostic tools in myelofibrosis (MF) fail to identify patients at the highest risk of death and are limited by their applicability only to the time of diagnosis. We aimed to define an accelerated phase (AP) in MF by characterizing disease features that can identify patients with median overall survival of or= 10%, platelets less than 50 x 10(9)/L, and chromosome 17 aberrations (median overall survival, 10, 12, and 5 months, respectively). In the validation phase, chronic-phase patients who developed AP features during follow-up were found to have short subsequent survival times (median overall survival, 12, 15, and 6 months, respectively). AP was a necessary step in the progression to blast phase, with leukemic transformation being exceedingly rare (3% risk at 10 years) in patients who remained persistently in chronic phase. CONCLUSION: Blood or bone marrow blasts >or= 10%, platelets less than 50 x 10(9)/L, and chromosome 17 aberrations defined AP in patients with MF. Patients in AP should be candidates for intensive therapeutic interventions.