Statistical Analysis
Models including predictors that were not included in the MR CLEAN Registry database were reconstructed from available variables if possible. If this was not possible, these models were included in the overview, but excluded for external validation.Model performance was evaluated with discrimination and calibration. Discrimination was quantified with the concordance (c) statistic, which is identical to the area under the receiver operating curve for binary outcomes. The c statistic varies between 0.5 for a non-informative model and 1 for a perfectly discriminating model.For models that were presented as a risk score, we used the predicted probabilities of each model as published in the original development article. If a study expressed a probability of 0 (0%) for the outcome of interest, this value was adapted to 0.01 (1%), because these probabilities were otherwise excluded by the Missing values were imputed with multiple imputation (n=5) using the function All statistical analyses were performed with R statistical software (version 4.0.5).