Facilitating International Participation in Core Outcome Set Development: A Proposed Approach for Multi-language Delphi Surveys, a Review of Current Practice and Issues to Consider

Abstract Background Core outcome sets (COS) should be relevant to key stakeholders and widely applicable so that researchers are willing to use them when designing trials. Many COS developers have utilised online Delphi surveys which enable wider international stakeholder participation. Despite broader participation, most international COS projects have restricted Delphi surveys to a single language potentially excluding important opinion from those who are not fluent in the survey language.Methods A structured review of current approaches to translating Delphi surveys for COS development was undertaken. We present a proposed methodology adapted from international guidance. Results Four studies were identified from our structured review. Wide variation exists in the methodological approaches to translating Delphi surveys for the developing of COS. Issues which arise when developing multi-language Delphi surveys include establishing translation groups, timelines, financial implications, strategies to maximise recruitment and regulatory approvals.Conclusion Consideration of the issues described will improve planning by other COS developers and can be used to widen international participation from both patients and healthcare professionals.