The following characteristics were selected for inclusion in the prognostic model based on the data collected from our 418-patient cohort. Spleen size and white blood cell count at the time of therapy initiation were the strongest predictors of early response to JAK2 inhibitor therapy. Achievement of an early response was used to further enhance the model for the late time point (third column) and was the strongest predictor of late response. Interaction terms looked at the interdependence of variables on splenic response. Log odds ratios are provided with 95% credible intervals in parentheses.