![Classification tree analysis with bootstrap for aGVHD GR2-4 at day +100. Classification tree analysis of the developmental cohort is shown (n = 128) (the validation cohort [n = 56] is not included). This method uses recursive partitioning based on the Gini purity index and enables the identification of variables that best predict GR2-4 aGVHD. Each box represents a node (second row in a box: the percentage of GR2-4 aGVHD within the node; third row in a box: sample size of the node and fraction of the initial node size). The initial tree was pruned per the crossvalidated error to avoid overfitting. The final model predicts the risk of aGVHD GR2-4 at day +100 by Ctrough_1 ≥39 vs <39 μg/mL (31% vs 62%). Ctrough_1 was identified as the most predictive classifier in 73.6% of the 1000 bootstrap data sets. Of these, the median Ctrough_1 threshold value was 39.0 μg/mL (95% CI, 24.1-50.9). BuCy, busulfan/cyclophosphamide; BuFlu, busulfan/fludarabine; CyTBI, cyclophosphamide/total body irradiation; FluMel, fludarabine/melphalan.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/142/8/10.1182_blood.2023020035/2/blood_bld-2023-020035-gr1.jpeg?Expires=1742847452&Signature=KEKUKznidt7mWMorFPjXc1wkUOjss3yeiEDdfpHnP2sESpq7meKeWpW3FXxDhLaOzqTGz0Al~oJ-ARGPRsCgo6d-l8tvVLvECYNNXngMZAKKEVpmO4YWctxWiqPxENnkYhXe2TVB3gwp8I3zdBOzHeQjYV1W8Uq4hBpjzXncxn98S8t2g-DN6DZ5fphuKbBEYDwYbEgBeZUapgakVZaLhSZ19qk5GbQphGGpEwdgArOho5W0d7c7quw80KQg-D~tDSA0n5OCBJQll6eMOENIq2W~8bX5I~LrG8FxuIhaZkoY7TtGwYwUhFoyMDC8wo6Y5RLXj2Pprv2hVXKk~TEgqA__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Classification tree analysis with bootstrap for aGVHD GR2-4 at day +100. Classification tree analysis of the developmental cohort is shown (n = 128) (the validation cohort [n = 56] is not included). This method uses recursive partitioning based on the Gini purity index and enables the identification of variables that best predict GR2-4 aGVHD. Each box represents a node (second row in a box: the percentage of GR2-4 aGVHD within the node; third row in a box: sample size of the node and fraction of the initial node size). The initial tree was pruned per the crossvalidated error to avoid overfitting. The final model predicts the risk of aGVHD GR2-4 at day +100 by Ctrough_1 ≥39 vs <39 μg/mL (31% vs 62%). Ctrough_1 was identified as the most predictive classifier in 73.6% of the 1000 bootstrap data sets. Of these, the median Ctrough_1 threshold value was 39.0 μg/mL (95% CI, 24.1-50.9). BuCy, busulfan/cyclophosphamide; BuFlu, busulfan/fludarabine; CyTBI, cyclophosphamide/total body irradiation; FluMel, fludarabine/melphalan.
