Time to disease progression in study patients population. Kaplan-Meier estimate of the time to disease progression in pre-PMF and overt PMF (A). Time to progression was defined as the time to acquisition of any 1 (except age) of the prognostically adverse clinical and hematologic variables included in the DIPSS-Plus score (anemia; leukocytosis; blasts ≥1% in peripheral blood; thrombocytopenia; appearance of constitutional symptoms; transfusion dependence; we did not consider adverse cytogenetics for which we had too few data). (B) Cumulative incidence for each of the individual prognostically unfavorable variables is shown. Cumulative incidence was estimated with a competing risk approach, considering death for any other cause as a competing event. Vertical tick marks indicate right-censored patients.