Objectives: To develop a core outcome set (COS) to capture and measure the well-being of doctors working in the NHS. Design: An online Delphi study. Setting: United Kingdom National Health Service. Participants: Participants from four stakeholder groups: i) those who might use the COS in research, ii) organisations that measure/capture NHS staff wellbeing, iii) professionals with experience managing NHS staff wellbeing, and iv) NHS doctors, were identified through authorship of relevant publications, attendee lists of doctor well-being conferences and meetings, professional bodies, participation in a previous study and recommendations from others. They were recruited via email. Method: A two-stage process: 1) creating a list of 43 wellbeing outcomes informed by a systematic review of wellbeing measurement instruments, a survey of UK doctors and 2 doctor engagement workshops, and 2) an online modified Delphi study (with two rounds) to reach consensus. Outcomes were rated on a 9-point Likert scale; consensus was reached when ≤75% agreed that an outcome was critical for inclusion in the COS. Results: Fifty-two participants completed both Delphi rounds. Seven wellbeing outcomes met the threshold for inclusion in the COS: General wellbeing, Health, Personal safety, Job satisfaction, Morale, Life work balance, and Good clinical practice. Conclusion: Use of the COS has the potential to reduce heterogeneity and standardise the capture and measurement of doctor well-being and ensure outcomes important to all stakeholders are reported. Trial registration: This study was prospectively registered with the COMET initiative www.comet-initiative.org (Registration: 1577)

The authors have declared no competing interest.

Health Education England (HEE) South provided financial support for this research in the form of a postgraduate fellowship awarded to GS. NK is funded by the National Institute for Health Research (NIHR) Applied Research Collaboration Wessex (ARC Wessex). For the purpose of open access, the author has applied a CC BY NC public copyright licence to any Author Accepted Manuscript arising from this submission.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

University of Southampton Faculty of Medicine Ethics Committee (ERGO 55747). Approved on 31/12/2021.

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