STUDY PROTOCOL Healthcare resource utilisation and mortality outcomes in international migrants to the UK: analysis protocol for a linked population-based cohort study using Clinical Practice Research Datalink (CPRD), Hospital Episode Statistics (HES) and the Office for National Statistics (ONS) [version 1; peer review: 1 approved with reservations, 1 not approved] Neha Pathak 1-4 , Parth Patel 1,2 , Rachel Burns 1,2 , Lucinda Haim 1,2 , Claire X. Zhang 1,3 , Yamina Boukari 1 , Arturo Gonzales-Izquierdo 1,2 , Rohini Mathur 5 , Caroline Minassian 5 , Alexandra Pitman 6 , Spiros Denaxas 1,2,7 , Harry Hemingway 1,2 , Andrew Hayward 3 , Pam Sonnenberg 8 , Robert W. Aldridge 1-3 1 Institute of Health Informatics, University College London, London, NW1 2DA, UK 2 Health Data Research UK, London, UK 3 Institute of Epidemiology & Healthcare,, University College London, London, WC1E 6BT, UK 4 Guy’s & St Thomas’s NHS Foundation Trust, London, SE1 9RT, UK 5 London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK 6 Division of Psychiatry, University College London, London, W1T 7BN, UK 7 The Alan Turing Institute, London, NW1 2DB, UK 8 Institute of Global Health, University College London, London, WC1E 6JB, UK First published: 03 Jul 2020, 5:156 https://doi.org/10.12688/wellcomeopenres.15931.1 Latest published: 24 May 2021, 5:156 https://doi.org/10.12688/wellcomeopenres.15931.2 v1 Abstract An estimated 14.2% (9.34 million people) of people living in the UK in 2019 were international migrants. Despite this, there are no large- scale national studies of their healthcare resource utilisation and little is known about how migrants access and use healthcare services. One ongoing study of migration health in the UK, the Million Migrants study, links electronic health records (EHRs) from hospital-based data, national death records and Public Health England migrant and refugee data. However, the Million Migrants study cannot provide a complete picture of migration health resource utilisation as it lacks data on migrants from Europe and utilisation of primary care for all international migrants. Our study seeks to address this limitation by Open Peer Review Reviewer Status Invited Reviewers 1 2 version 2 (revision) 24 May 2021 report version 1 03 Jul 2020 report report Page 1 of 21 Wellcome Open Research 2020, 5:156 Last updated: 20 JAN 2022