Mortality risk prediction models: Methods of assessing discrimination and calibration and what they mean

Mortality prediction models, which this author prefers to call outcome-risk assignment models, are ubiquitous in critical care practice. They are designed to assess the risk of dying for any given patient by assigning risk based on indices of physiological derangement, high-risk diagnoses or diagnostic categories, or the need for therapeutic intervention to support organ function. It is important to recognise that predictive models derived to date are not accurate enough to allow reliable prediction of individual patient outcome, and therefore cannot be used as criteria for admission to intensive care. Patients identified as high risk for mortality must be flagged for appropriate intensive intervention and close monitoring in order to reduce the risk of dying due to the current illness.