Development of a core outcome set for informed consent for therapy: An international key stakeholder consensus study

300 million operations and procedures are performed annually across the world, all of which require a patient's informed consent. No standardised measure of the consent process exists in current clinical practice. We aimed to define a core outcome set for informed consent for therapy.

The core outcome set was developed in accordance with a predefined research protocol and the Core OutcoMes in Effectiveness Trials (COMET) methodology comprising systematic review, qualitative semi structured interviews, a modified Delphi process and consensus webinars to ratify outcomes for inclusion in the final core outcome set. (Registration- https://www.comet-initiative.org/Studies/Details/1024 ). Participants from all key stakeholder groups took part in the process, including patients and the public, healthcare practitioners and consent researchers.

36 outcome domains were synthesised through systematic review and organised into a consent taxonomy. 41 semi-structured interviews were performed with all consent stakeholders groups. 164 participants from all stakeholder groups across 8 countries completed Delphi Round 1 and 125 completed Round 2. 11 outcomes met the 'consensus in' criteria. 6 met 'consensus in' all stakeholder groups and were included directly in the final core outcome set. 5 remaining outcomes meeting 'consensus in' were ratified over two consensus webinars. 9 core outcomes were included in the final core outcome set: Satisfaction with the quality and amount of information, Patient feeling that there was a choice, Patient feeling that the decision to consent was their own, Confidence in the decision made, Satisfaction with communication, Trust in the clinician, Patient satisfaction with the consent process, Patient rated adequacy of time and opportunity to ask questions.

This international mixed-methods qualitative study is the first of its kind to define a core outcome set for informed consent for intervention. It defines what outcomes are of importance to key stakeholders in the consent process and is a forward step towards standardising future consent research.