More recently, individualized prediction models have been developed in psychiatry, 4 and a new field of precision psychiatry has emerged. 5 External validity is the extent to which the predictions can be generalized to the data from plausibly related settings, while internal validity is the extent to which the predictions fit the derivation data after controlling for overfitting and optimism, with the latter representing the difference in a model’s performance in the derivation data and unseen individuals (for further details see 4). From a methodological perspective, individualized prediction modeling research includes studies that investigate the development, internal or external validation of prediction models, and prediction model impact studies, which investigate the real-world effect of using prediction models in clinical practice. 4 Prediction modeling can be used to forecast the probability of a certain condition being present (diagnostic models), outcomes (prognostic models), or the response to interventions (predictive models) at the individual subject level. 3 Yet, modern advancements of knowledge in the field of individualized prediction modeling have allowed the consolidation of an evidence-based science of precision medicine. 1, 2 The concept of precision medicine is not new clinicians have been working to personalize care tailored to people’s individual health needs throughout the history of medicine (eg, matching human blood groups across donors and recipients during blood transfusion). Precision medicine is an emerging approach for disease prevention, diagnosis, and treatment that considers individual variability in patient and disease characteristics, genes, environment, and lifestyle of each person.

Prognostic vs predictive