Editor's choice - June 2023.

A core outcome set can be defined as “a standardised set of outcomes which should be measured and reported, as a minimum, in all effectiveness trials for a specific health area [[1]Gargon E. Gurung B. Medley N. Altman D.G. Blazeby J.M. Clarke M. Williamson P.R. Choosing important health outcomes for comparative effectiveness research: a systematic review.PLoS One. 2014; 9e99111Crossref PubMed Scopus (233) Google Scholar].” Core outcome sets are important because they ensure that the most relevant outcomes to all users of research, such as patients and the public, healthcare providers, policy-makers, researchers, and funders are included [[2]Kearney A. Gargon E. Mitchell J.W. Callaghan S. Yameen F. Williamson P.R. Dodd S. A systematic review of studies reporting the development of core outcome sets for use in routine care.J Clin Epidemiol. 2023; 158: 34-43Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar]. An international effort to regularly update core outcome sets in trials is the COMET initiative–which stands for Core Outcome Measures in Effectiveness Trials (https://www.comet-initiative.org). COMET aims to identify problems with outcomes in trials, encourage the evidence-based development of core outcome sets along with their uptake, support the inclusion of patients and public partners in the development of core outcome sets, and reduce research waste (https://www.comet-initiative.org/About/WhatWeDo). Resources are provided to achieve these goals (https://www.comet-initiative.org/About/WhatWeDo). The JCE has published several methodological papers on core outcome sets, including a previous Editor's Choice article entitled “Whither Core Outcome Sets [[3]Tugwell P. Knottnerus J.A. Whither core outcome sets?.J Clin Epidemiol. 2014; 67: 731-733Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar]”. This article provides a historical summary of the use of core outcome sets and outlines relevant initiatives globally. In addition, the JCE published a Controversy and Debates series on issues of relevance to core outcome sets, which provides additional challenges with their development [[4]Chevance A. Tran V.T. Ravaud P. Controversy and debate series on core outcome sets. Paper 7: response to comments on the paper 2-6 re “improving the generalizability and credibility of core outcome sets (COSs) by involving large international sample of participants”.J Clin Epidemiol. 2020; 125: 232-234Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar]. Examples include increasing the generalizability of core outcome sets through large international online surveys [[4]Chevance A. Tran V.T. Ravaud P. Controversy and debate series on core outcome sets. Paper 7: response to comments on the paper 2-6 re “improving the generalizability and credibility of core outcome sets (COSs) by involving large international sample of participants”.J Clin Epidemiol. 2020; 125: 232-234Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar], use of large-scale, mixed-methods knowledge exchange [[5]Carter S.A. Tong A. Gutman T. Scholes-Robertson N. Teixeira-Pinto A. Howell M. Craig J.C. Controversy and Debate Series on Core Outcome Sets. Paper 5: large-scale, mixed-methods, knowledge exchange to establish core outcomes - the SONG approach.J Clin Epidemiol. 2020; 125: 225-228Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar] to develop core outcome sets, and ensuring the core outcome set is feasible by only including the most crucial outcome measures deemed most important [[6]Schmitt J. Kottner J. Lange T. Controversy and debate series on core outcome sets. Paper 6: improving the generalizability, credibility and implementation of core outcome sets - the example of the Cochrane skin-core outcome set initiative (CS-COUSIN).J Clin Epidemiol. 2020; 125: 229-231Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar]. The perspectives from the Outcome Measures in Rheumatology (OMERACT [[7]Maxwell L.J. Beaton D.E. Controversy and debate series on core outcome sets. Paper 2: debate on paper 1 from the perspective of OMERACT [outcome measures in rheumatology].J Clin Epidemiol. 2020; 125: 213-215Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar], Grading of Recommendations Assessment, Development and Evaluation (GRADE [[8]Schünemann H.J. Tunis S. Nieuwlaat R. Wiercioch W. Baldeh T. Controversy and debate series on core outcome sets. Paper 3: debate on paper 1 from the perspective of GRADE [grading of recommendations assessment, development and evaluation].J Clin Epidemiol. 2020; 125: 216-221Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar]), and Core Outcome Measures in Effectiveness Trials (COMET [[9]Williamson P.R. Blazeby J.M. Brookes S.T. Clarke M. Terwee C.B. Young B. Controversy and debate series on core outcome sets. Paper 4: debate on paper 1 from the perspective of COMET [core outcome measures in effectiveness trials].J Clin Epidemiol. 2020; 125: 222-224Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar]) initiatives on these suggestions were also provided. In the most recent issue of the JCE, three papers focused on additional issues relevant to core outcome sets. The first paper looked at the scope, user involvement, and methods used to develop core outcome sets in routine care [[2]Kearney A. Gargon E. Mitchell J.W. Callaghan S. Yameen F. Williamson P.R. Dodd S. A systematic review of studies reporting the development of core outcome sets for use in routine care.J Clin Epidemiol. 2023; 158: 34-43Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar]. The second paper assessed the impact of including patients and the public in development core outcome sets [[10]Dodd S. Gorst S.L. Young A. Lucas S.W. Williamson P.R. Patient participation impacts outcome domain selection in core outcome sets for research: an updated systematic review.J Clin Epidemiol. 2023; 158: 127-133Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar]. And the third paper examined the impact of a national funding agency's guidance on core outcome sets on their uptake [[11]Beecher C. Galvin S. Cody A. Williamson P.R. Hughes K. Ward O. Creely C. Devane D. Irish funder guidance increased searching for, and uptake of, core outcome sets.J Clin Epidemiol. 2023; 158: 92-98Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar]. Kearney et al., 2023 [[2]Kearney A. Gargon E. Mitchell J.W. Callaghan S. Yameen F. Williamson P.R. Dodd S. A systematic review of studies reporting the development of core outcome sets for use in routine care.J Clin Epidemiol. 2023; 158: 34-43Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar] conducted a systematic review to examine all core outcome sets that were developed for routine care topics only. The definition of routine care was data collected for clinical practice and not solely for the purpose of research. Their aim was to identify what the scope of these projects were, as well as chart the methods used, and identify the users involved with their development. After screening more than 25,000 citations across several databases, 164 core outcome sets were identified specific to routine care only, whereas 98 core outcome sets were identified that were relevant to both routine care plus research. The most common clinical areas for the core outcome sets were heart and circulation, cancer, and orthopedics and trauma. To gather evidence for the core outcome sets, the most common method was through the literature or through seeking information from patient and public partners; the Delphi was the most common approach for establishing agreement on the final list of core outcomes. Most of the core outcome sets included expertise from clinicians, whereas half included patient and public partners. The authors found that the number of core outcome sets being produced for routine care increased over time. Dodd and colleagues, 2023 [[10]Dodd S. Gorst S.L. Young A. Lucas S.W. Williamson P.R. Patient participation impacts outcome domain selection in core outcome sets for research: an updated systematic review.J Clin Epidemiol. 2023; 158: 127-133Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar] examined the impact of involving patients and the public in the development of core outcome sets using updated systematic reviews that were conducted as part of the COMET initiative. The updates included 56 new studies that were published in 2020 and 54 new studies that were published in 2021. The total number of patient and public partners involved with the core outcome set development increased; with 79% of the 56 new studies included in the 2020 update and 85% of the 54 new studies that were included in the 2021 update. Similar to Kearney et al. [[2]Kearney A. Gargon E. Mitchell J.W. Callaghan S. Yameen F. Williamson P.R. Dodd S. A systematic review of studies reporting the development of core outcome sets for use in routine care.J Clin Epidemiol. 2023; 158: 34-43Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar], the majority of the core outcome sets included clinicians and researchers in their development and employed a Delphi approach to select the outcomes for inclusion. Core outcome sets with and without patient and public involvement were compared. The ones that included patients and the public were more likely to include life impact outcomes, such as function and quality of life, compared to core outcome sets that did not include patient and public partners. Lastly, in Beecher et al., 2023 [[11]Beecher C. Galvin S. Cody A. Williamson P.R. Hughes K. Ward O. Creely C. Devane D. Irish funder guidance increased searching for, and uptake of, core outcome sets.J Clin Epidemiol. 2023; 158: 92-98Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar], the impact of the Health Research Board of Ireland's guidance to incorporate core outcome sets in trials was assessed by reviewing grant applications submitted to this national funding agency. The research entailed three distinct phases: 1) a search for trial grant applications in the national funding agency's database, 2) a search of the COMET database to see if a relevant core outcome set relevant to the trial grant application was available around the same time, and 3) a survey of the principal applicant of the trial grant application for further information. There was a total of 111 relevant grant applications submitted between 2004 and 2018, which were compared with 76 relevant grants submitted in 2020. The reason for this date comparison was that the Health Research Board of Ireland included additional questions related to core outcome sets in 2020 and specifically encouraged researchers to search the COMET database at this time. Between 2004 and 2018, 58% of the applications reported including patients and the public in their study design, yet only 3% explicitly reported the details related to how the input of patient and public partners was sought on the core outcome sets. There were 76 applications submitted in 2020 and 82% reported seeking the input from patient and public partners, yet only 11% reported the explicit details on how this was done. Of the 111 applications between 2014 and 2018, only 6% reported searching the COMET database. In contrast, 99% of the 76 2020 applications reported doing so. The results of these papers indicate the importance of including patients and the public in the development of core outcome sets. This is helpful in shaping what outcomes are eventually included, with life impact outcomes of greater importance to patients and the public [[10]Dodd S. Gorst S.L. Young A. Lucas S.W. Williamson P.R. Patient participation impacts outcome domain selection in core outcome sets for research: an updated systematic review.J Clin Epidemiol. 2023; 158: 127-133Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar]. Most core outcome sets include clinicians and researchers in their development and use a Delphi approach to select the outcomes for inclusion [[10]Dodd S. Gorst S.L. Young A. Lucas S.W. Williamson P.R. Patient participation impacts outcome domain selection in core outcome sets for research: an updated systematic review.J Clin Epidemiol. 2023; 158: 127-133Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar]. Finally, national funding agencies can increase the consideration of core outcome sets by specifically asking researchers to consider important items, such as searching the COMET database, as outlined in Beecher et al., 2023 [[11]Beecher C. Galvin S. Cody A. Williamson P.R. Hughes K. Ward O. Creely C. Devane D. Irish funder guidance increased searching for, and uptake of, core outcome sets.J Clin Epidemiol. 2023; 158: 92-98Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar].