IWG-MRT prognostic score for myelofibrosis              
Applies at the time of diagnosis.
  Value     1. Sum the number of adverse prognostic factors  
Age (years)*
Age > 65 y
WBC count (x 109/L)*
Constitutional symptoms
Hemoglobin (x g/dL)*
Hemoglobin <10 g/dL
Peripheral blood blasts (% of leukocytes)*
WBC count > 25 × 109/L
Constitutional symptoms
Circulating blasts >1%
          2. Determine IWG-MRT risk group and prognosis
IWG-MRT score       Number of factors Risk group Pro­portion of patients Median OS (m)
IWG-MRT risk group       0 Low 22 135
1 Inter­mediate-1 29 95
2 Inter­mediate-2 28 48
≥ 3 High 21 27
Cervantes F, Dupriez B, Pereira A, Passamonti F, Reilly JT, Morra E et al. New prognostic scoring system for primary myelofibrosis based on a study of the International Working Group for Myelofibrosis Research and Treatment. Blood 2009; 113: 2895-2901.