Ewen is Professor of Surgery and Data Science at the University of Edinburgh and a Consultant HPB Surgeon at the Royal Infirmary of Edinburgh.

His interests focus on data, technology and artifical intelligence, including mobile data collection platforms and "wearables", decision modelling, Bayesian statistics, and trials, particularly low resource settings.

He leads the NIHR Unit on Global Surgery at the University of Edinburgh, a collaboration with the University of Birmingham with partners in seven countries: Benin, Ghana, India, Mexico, Nigeria, Rwanda, South Africa.

This provides a platform for the GlobalSurg Collaborative (globalsurg.org), which holds the Guinness Record as the world’s largest scientific collaboration, with over 15,000 collaborators across over 1000 hospitals in over 100 countries ). He has supported and trained surgical research teams across Africa and Asia, including Ghana, Nigeria, Rwanda, and India, recently completing the largest ever international study in cancer surgery (Lancet, January 2021).

In the UK he leads the Centre for Medical Informatics and during the pandemic he headed the analytics for two of the largest COVID-19 cohorts in the world (ISARIC4C and PHOSP-Covid). He advised UK governments including through the Scientific Advisory Group for Emergencies (SAGE) and his work has been widely reported in the media: his 4C Mortality risk prediction score was validated in >22 countries and used by clinical teams internationally, demonstrably optimizing the care that COVID-19 patients receive in hospital.