Table 1.

Summary of methods used to develop a core outcome set

Phase 1	Identification of all outcomes that may be measured following reconstructive breast surgery
	Systematic literature searches to identify clinical outcomes, patient‐reported and cosmetic outcomes
	Qualitative interviews with patients and healthcare professionals regarding which outcomes they feel should be measured following reconstructive breast surgery
	This produces a list of all potential outcomes
	The list is grouped into outcome domains to avoid repetition
	The domains inform questionnaire items to use in phase 2
Phase 2	Prioritization of outcomes by key stakeholders – Delphi survey
	Stakeholders are surveyed and asked to prioritize each outcome
	Results of the survey are fed back to stakeholders in a second survey (Delphi methods) and they are asked to reprioritize each outcome
	Data are analysed by the research group using predefined criteria to reduce the list of information
	This produces two outcome lists (from patients and healthcare professionals) ready for phase 3
Phase 3	Consensus meetings are held separately with key stakeholder groups
	The items are presented to each group and items are rated as, ‘in’, ‘out’ or ‘unsure’ during anonymized voting
	Items rated as ‘unsure’ are discussed and more voting is undertaken
	The process produces two sets (1 selected by patients, 1 by professionals). These are compared and combined into one outcome set