Predicting long-term survival in primary myelofibrosis.

We interrogated data from 217 subjects with primary myelofibrosis (PMF) diagnosed before 2001 to identify covariates at diagnosis associated with long-term survival. Forty-one survived more than 25 years. Long-term survivors were more often female, younger than 50 years and less likely to have anemia, splenomegaly, increased blood CD34-positive cells, a JAK2V617F variant, and more likely to have grade-0 bone marrow fibrosis and increased platelets. In multivariable logistic regression analyses, age <50 years, platelet count >450 × 10⁹/L, and grade-0 bone marrow fibrosis independently predicted long-term survival. These co-variate associations were confirmed in Cox regression with landmark analyses. Long-term survivors had a lower cumulative incidence of anemia and thrombocytopenia during follow-up. Identifying long-term survivors at diagnosis provides clinically meaningful prognostic information in PMF and may influence therapy decisions.