equal fold sizes, ranging between 0.56 (95% CI = 0.45–0.67; pcorrected > 0.99) and 0.62 (95% CI = (0.51–0.73); pcorrected = 0.55). However, variance across CV-folds was higher and comparable to that from LOSO-CV (SD; site-stratified fixed: 0.02–0.04; site-stratified variable: 0.05–0.08; LOSO: 0.07–0.11). A complete overview of classification results is provided in supplementary Table S2. Multi-site classification with site-stratified CV (with equal fold sizes), performed separately on pediatric and adult samples yielded similar results, ranging from 0.55 (95% CI = 0.43–0.67; pcorrected = 1) to 0.62 (95% CI = 0.51–0.74; pcorrected = 0.71) and 0.56 (95% CI = 0.5–0.62; pcorrected = 0.69) to 0.61 (95% CI = 0.55–0.67; pcorrected = 0.008) AUC, respectively (see supplementary Tables S3-4). As site-stratified CV with equal fold-sizes resulted in the best performances, we used this strategy for further evaluation of intra-site performance and the influence of clinical variables. RFC classification performance is reported here by default, as differences between classifiers were minimal and this model was also used to extract feature importance.
