Evaluation of clinical prediction models (part 3): calculating the sample size required for an external validation study

Riley, Richard; Snell, Kym IE; Archer, Lucinda; Ensor, Joie; Debray, Thomas PA; Van Calster, Ben; van Smeden, Maarten; Collins, Gary S

doi:10.1136/bmj-2023-074821

Evaluation of clinical prediction models (part 3): calculating the sample size required for an external validation study

Author:

Riley, Richard

Snell, Kym IE ; Archer, Lucinda ; Ensor, Joie ; Debray, Thomas PA ; Van Calster, Ben ; van Smeden, Maarten ; Collins, Gary S

Keywords:

Science & Technology, Life Sciences & Biomedicine, Medicine, General & Internal, General & Internal Medicine, PROGNOSTIC MODELS, CALIBRATION, Humans, Sample Size, Models, Statistical, Prognosis, G097322N#56765041, 1103 Clinical Sciences, 1117 Public Health and Health Services, 32 Biomedical and clinical sciences, 42 Health sciences, 52 Psychology

Abstract:

An external validation study evaluates the performance of a prediction model in new data, but many of these studies are too small to provide reliable answers. In the third article of their series on model evaluation, Riley and colleagues describe how to calculate the sample size required for external validation studies, and propose to avoid rules of thumb by tailoring calculations to the model and setting at hand.