It is crucial that the outcomes used in clinical effectiveness studies are relevant to patients. This relevance can be assured by patients participating with other key stakeholders in core outcome set (COS) studies, yet recruiting patients to such studies can be challenging.

As no guidance currently exists to help COS developers create good COS invitations for patients, which are usually the first documents patients see when invited to participate in COS studies, the Good Research Invitation Study aimed to produce such guidance.

Consensus meeting to agree on guidance for COS developers designing research invitations.

Informed by findings from our previous qualitative study of patient and public opinions on COS study invitations, our team, which included a patient research partner, produced an initial set of candidate recommendations. An online consensus meeting was organised in the UK with 13 participants including patient research partners with and without COS study experience, COS developers, a representative from an ethics committee and experts in diversity, marketing and science communication. Through a process of discussion and voting, the initial set of recommendations was refined.

From the initial 35 recommendations, consensus meeting participants agreed a final set of 22 recommendations. Some initial recommendations were removed as they were beyond the scope, while others were merged. The finalised recommendations focused on producing and user testing invitations, reaching the audience, engaging potential COS participants and considering what they might find appealing or off-putting, explaining and creating interest in the study, keeping the invitation simple and understandable, considering the amount of information to include and how to present it, alongside ensuring accessibility. Discussion during the meeting highlighted the importance of improving the accessibility of all participant-facing resources in COS studies, not just the invitations.

Through consensus, a set of recommendations has been agreed on for use by COS developers to enhance study invitations for patients. Further testing and refinement of the recommendations will improve their utility.

The use of core outcome sets (COSs) in health research is widely recommended. COSs are developed with input from key decision makers, patients being a vital group to ensure COS relevance. However, recruitment to COS studies can be challenging.

The study aimed to explore what patients and the public think of COS study invitations, which are usually the first document a patient reads about a COS study.

Qualitative study involving focus groups and interviews. Analysis of transcribed data drew on reflexive thematic analysis.

Focus groups and interviews were conducted with a diverse range of patients and the public (n=31) from community and patient groups in North West England, exploring their perceptions of a sample of COS study invitations. Participants were eligible if aged over 18 years, they could speak English and had never previously participated in a COS study.

Themes identified included understanding, engagement, safety and accessibility. Participants were concerned about excessive information in the invitations which made them confused. Fear of cybercrime caused numerous concerns and participants were reluctant to click on links or attachments. Trust in the people sending the invitations was key. Participants wanted to see messages that COS studies had a meaningful purpose to feel their contributions were valuable. They were keen to contribute to improving future ‘treatment’ but less motivated to improve ‘research’. Messages that evoked a feeling of connection with others who they could relate to were positively regarded. Participants also highlighted ways that invitations could be made more accessible.

COS invitations can present numerous challenges for potential participants, but our study indicates ways that COS developers can address these challenges and make their invitations more appealing to potential participants. As part of the wider Good Research Invitation Study the findings have been used to inform guidance on designing a good COS invitation