Fig. 4

A summary of methodological guidance for model updating. Simple updating (e.g., recalibration) is often sufficient when the differences between the derivation and new data are minimal. When the differences are more substantial, more extensive updating (e.g., partial to full revision) may be appropriate. Model extension allows the incorporation of new markers in a model. Multiple models may be combined, for instance, using meta-analytical approaches, to develop a meta-model that can be further updated for a new dataset. Updating can also be done periodically or continuously, resulting in dynamically updated models