In the multivariate Cox regression models adjusted for sex, high-risk disease, presence of CV risk factors, JAK2 mutation, baseline leukocytosis, and cytoreductive treatment, polypharmacy (HR 7.60, p = 0.008) and DDIs (HR 5.00, p = 0.025) remained as predictors of an inferior TTT, as presented in Supplementary Table S4. Here, JAK2 is linked to Increased total leukocyte count.