Kaplan-Meier analysis of survival of PMF patients stratified according to their driver mutation. Vertical tick marks indicate right-censored patients. In univariate analysis, CALR-mutant patients had a better OS than JAK2-mutant (HR 2.3, P < .001), MPL-mutant (HR 2.6, P = .009), and triple-negative patients (HR 6.2, P < .001). Three JAK2-mutant patients had short follow-up and were not included in the analysis.