Patient digital twins: an introduction based on a scoping review

The concept of digital twins, widely adopted in industry, is entering healthcare. In this scoping review, we analysed definitions and characteristics of patient digital twins being developed for clinical use. Searching for studies claiming digital twin development/evaluation until August 2023, we identified 86 articles representing 80 unique claimed digital twins, nearly all (98%) in preclinical phases. From the analysis of definitions and characteristics, we propose to define patient digital twin as "a viewable digital replica of a patient, organ, or biological system that contains multidimensional, patient-specific information". Two main forms were found: simulation digital twins using computational modelling of patient anatomy/physiology to run personalised outcome predictions and therapy evaluations, mostly for one-time assessments; and monitoring digital twins harnessing aggregated patient data for continuous risk/outcome forecasting over time and care optimisation. As patient digital twins rapidly emerge, the proposed definitions and subtypes offer a framework to guide research into realising the potential of these personalised, integrative technologies to advance clinical care.