Dxy is a measure of correlation varying between −1 and 1, with 0 indicating no correlation, and 1 perfect concordance of prognosis and survival, respective to time to transformation (see also the short explanation of Dxy in the supplemental Data). Dxy values were tabulated conditional on minimum observation time for potential predictors and composite scores. Changes in Dxy values are consistent with hazard plots (Figures 1, 2, 4, and 5) and show similar loss of prognostic power over time. Scores with high initial prognostic power, even if decreasing over time, remained prognostically stronger than initially weaker scores. With respect to single parameters, bone marrow blast percentage is the strongest single predictor. Its predictive loss over time is consistent with most other parameters and scores. Cytogenetic pattern is of high importance at time of diagnosis with steady loss of prognostic power. Age showed growing negative impact on survival, although not on time to AML progression. For hemoglobin, neutrophils, platelets, and bone marrow blasts, the cut points were those used for the IPSS-R. Age groups were categorized as ≤55, >55 to ≤65, >65 to ≤75, >75 to ≤80, and >80 years. For serum lactate dehydrogenase (LDH) and β₂-microglobulin, the upper limit of normal was the cut point; for serum ferritin, 350 ng/mL was the chosen cut point. Cytogenetic categories are those used in the IPSS-R. In lower risk denotes application of LR-PSS and IPSS-R on lower-risk patients (ie, IPSS-R very low, low, intermediate) only. IPSS-R WHO indicates that IPSS-R was exclusively applied to patients classifiable according to WHO. For dichotomization into 2 groups with higher- vs lower-risk patients, Dxy values for combined IPSS-R very-low-, low-, and intermediate-risk vs high- and very-high-risk patients and a cutoff at 3.5 IPSS-R score points (IPSS-R-DLH ≤3.5/>3.5) are tabulated.

DLH, dichotomizing lower vs higher risk; ECOG PS, Eastern Cooperative Oncology Group performance status.