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Abstract Background Missing outcome data or the inconsistent reporting of outcome data in clinical research can affect the quality of evidence within a systematic review. A potential solution is an agreed standardized set of outcomes known as a core outcome set (COS) to be measured in all studies for a specific condition. We investigated the amount of missing patient data for primary outcomes in Cochrane systematic reviews, and surveyed the Co-ordinating Editors of Cochrane Review Groups (CRGs) on issues related to the standardization of outcomes in their CRG’s reviews. These groups are responsible for the more than 7,000 protocols and full versions of Cochrane Reviews that are currently available, and the several hundred new reviews published each year, presenting the world’s largest collection of standardized systematic reviews in health care. Methods Using an unselected cohort of Cochrane Reviews, we calculated and presented the percentage of missing patient data for the primary outcome measure chosen for each review published by each CRG. We also surveyed the CRG Co-ordinating Editors to see what their policies are with regards to outcome selection and outcomes to include in the Summary of Finding (SoF) tables in their Cochrane Reviews. They were also asked to list the main advantages and challenges of standardizing outcomes across all reviews within their CRG. Results In one fifth of the 283 reviews in the sample, more than 50% of the patient data for the primary outcome was missing. Responses to the survey were received from 90% of Co-ordinating Editors. Thirty-six percent of CRGs have a centralized policy regarding which outcomes to include in the SoF table and 73% of Co-ordinating Editors thought that a COS for effectiveness trials should be used routinely for a SoF table. Conclusions The reliability of systematic reviews, in particular meta-analyses they contain, can be improved if more attention is paid to missing outcome data. The availability of COSs for specific health conditions might help with this and the concept has support from the majority of Co-ordinating Editors in CRGs.

Abstract The selection of appropriate outcomes or domains is crucial when designing clinical trials in order to compare directly the effects of different interventions in ways that minimize bias. If the findings are to influence policy and practice then the chosen outcomes need to be relevant and important to key stakeholders including patients and the public, health care professionals and others making decisions about health care. There is a growing recognition that insufficient attention has been paid to the outcomes measured in clinical trials. These issues could be addressed through the development and use of an agreed standardized collection of outcomes, known as a core outcome set, which should be measured and reported, as a minimum, in all trials for a specific clinical area. Accumulating work in this area has identified the need for general guidance on the development of core outcome sets. Key issues to consider in the development of a core outcome set include its scope, the stakeholder groups to involve, choice of consensus method and the achievement of a consensus.

Abstract Background Key stakeholders regard generic utility instruments as suitable tools to inform health technology assessment decision-making regarding allocation of resources across competing interventions. These instruments require a 'descriptor', a 'valuation' and a 'perspective' of the economic evaluation. There are various approaches that can be taken for each of these, offering a potential lack of consistency between instruments (a basic requirement for comparisons across diseases). The 'reference method' has been proposed as a way to address the limitations of the Quality-Adjusted Life Year (QALY). However, the degree to which generic measures can assess patients' specific experiences with their disease would remain unresolved. This has been neglected in the discussions on methods development and its impact on the QALY values obtained and resulting cost per QALY estimate underestimated. This study explored the content of utility instruments relevant to type 2 diabetes and Alzheimer's disease (AD) as examples, and the role of qualitative research in informing the trade-off between content coverage and consistency. Method A literature review was performed to identify qualitative and quantitative studies regarding patients' experiences with type 2 diabetes or AD, and associated treatments. Conceptual models for each indication were developed. Generic- and disease-specific instruments were mapped to the conceptual models. Results Findings showed that published descriptions of relevant concepts important to patients with type 2 diabetes or AD are available for consideration in deciding on the most comprehensive approach to utility assessment. While the 15-dimensional health related quality of life measure (15D) seemed the most comprehensive measure for both diseases, the Health Utilities Index 3 (HUI 3) seemed to have the least coverage for type 2 diabetes and the EuroQol-5 Dimensions (EQ-5D) for AD. Furthermore, some of the utility instruments contained items that could not be mapped onto either of the proposed conceptual models. Conclusions Content of the utility measure has a significant impact on the treatment effects that can be observed. This varies from one disease to the next and as such contributes to lack of consistency in observable utility effects and incremental utility scores. This observation appears to have been omitted from the method development considerations such as reference methods. As a result, we recommend that patients' perspectives obtained via qualitative methods are taken into consideration in the ongoing methods development in health state descriptions for generic utility instruments. Also, as a more immediate contribution to improving decision making, we propose that a content map of the chosen utility measure with patient-reported domains be provided as standard reporting in utility measurement in order to improve the transparency of the trade-offs in relation to patient relevance and consistency.

Background: Key stakeholders regard generic utility instruments as suitable tools to inform health technology assessment decision-making regarding allocation of resources across competing interventions. These instruments require a 'descriptor', a 'valuation' and a 'perspective' of the economic evaluation. There are various approaches that can be taken for each of these, offering a potential lack of consistency between instruments (a basic requirement for comparisons across diseases). The 'reference method' has been proposed as a way to address the limitations of the Quality-Adjusted Life Year (QALY). However, the degree to which generic measures can assess patients' specific experiences with their disease would remain unresolved. This has been neglected in the discussions on methods development and its impact on the QALY values obtained and resulting cost per QALY estimate underestimated. This study explored the content of utility instruments relevant to type 2 diabetes and Alzheimer's disease (AD) as examples, and the role of qualitative research in informing the trade-off between content coverage and consistency.Method: A literature review was performed to identify qualitative and quantitative studies regarding patients' experiences with type 2 diabetes or AD, and associated treatments. Conceptual models for each indication were developed. Generic- and disease-specific instruments were mapped to the conceptual models.Results: Findings showed that published descriptions of relevant concepts important to patients with type 2 diabetes or AD are available for consideration in deciding on the most comprehensive approach to utility assessment. While the 15-dimensional health related quality of life measure (15D) seemed the most comprehensive measure for both diseases, the Health Utilities Index 3 (HUI 3) seemed to have the least coverage for type 2 diabetes and the EuroQol-5 Dimensions (EQ-5D) for AD. Furthermore, some of the utility instruments contained items that could not be mapped onto either of the proposed conceptual models.Conclusions: Content of the utility measure has a significant impact on the treatment effects that can be observed. This varies from one disease to the next and as such contributes to lack of consistency in observable utility effects and incremental utility scores. This observation appears to have been omitted from the method development considerations such as reference methods. As a result, we recommend that patients' perspectives obtained via qualitative methods are taken into consideration in the ongoing methods development in health state descriptions for generic utility instruments. Also, as a more immediate contribution to improving decision making, we propose that a content map of the chosen utility measure with patient-reported domains be provided as standard reporting in utility measurement in order to improve the transparency of the trade-offs in relation to patient relevance and consistency. [ABSTRACT FROM AUTHOR]

Introduction: Several clinical outcome assessment (COA) instruments assess Sjögren's disease (Sjögren's) symptoms, but do not provide comprehensive assessment of the health-related quality of life (HRQoL) impact of Sjögren's. This study aimed to develop a patient-reported outcome (PRO) instrument for the assessment of HRQoL, intended for use in clinical trials and clinical practice in the assessment of treatment benefit., Methods: Review of study sponsor proprietary data and qualitative interviews informed the development of a conceptual model, the Sjögren's Related Quality of Life (SRQoL) and patient global impression of severity (PGI-S) and change (PGI-C) items. Combined concept elicitation and cognitive debriefing interviews with patients with Sjögren's explored their HRQoL impact experience and content validity of the SRQoL and PGI items., Results: Twenty participants were interviewed about their Sjögren's experience. Following inductive analysis of interviews, concepts were categorized into eight domains: emotional well-being (e.g., worry and stress; n = 20/20; 100%), sleep (e.g., daytime sleepiness and waking up during the night; n = 20/20; 100%), activities of daily living (e.g., difficulty looking at screens and difficulty driving; n = 20/20; 100%), cognition (e.g., concentration difficulties and word finding difficulties; n = 19/20; 95.0%), physical functioning (e.g., difficulty walking and difficulty exercising; n = 19/20; 95.0%), social and family functioning (e.g., dependent on others and relationship difficulties; n = 17/20; 85.0%), work (n = 15/20; 75.0%), and sexual functioning (n = 12/20; 60.0%). SRQoL and PGI items, instructions, response options, and recall period were well understood and relevant to participants., Conclusions: The SRQoL is a new PRO instrument to assess Sjögren's impact on HRQoL, developed in accordance with regulatory guidance. This study provides considerable insight into the patient experience of Sjögren's and evidence to support the content validity of the SRQoL. Future research should evaluate the psychometric properties of the SRQoL to support its use in clinical trials and clinical practice and further validate its use as an assessment of treatment benefit., (© 2024. The Author(s).)

Objectives: Core outcome sets (COS) represent the minimum health outcomes to be measured for a given health condition. Interest is growing in using COS within routine care to support delivery of patient-focused care. This review aims to systematically map COS developed for routine care to understand their scope, stakeholder involvement, and development methods., Methods: Medline (Ovid), Scopus, and Web of Science Core collection were searched for studies reporting development of COS for routine care. Data on scope, methods, and stakeholder groups were analyzed in subgroups defined by setting., Results: Screening 25,301 records identified 262 COS: 164 for routine care only and 98 for routine care and research. Nearly half of the COS (112/254, 44%) were developed with patients, alongside input from experts in registries, insurance, legal, outcomes measurement, and performance management. Research publications were often searched to generate an initial list of outcomes (115/198, 58%) with few searching routine health records (47/198, 24%)., Conclusion: An increasing number of COS is being developed for routine care. Although involvement of patient stakeholders has increased in recent years, further improvements are needed. Methodology and scope are broadly similar to COS for research but implementation of the final set is a greater consideration during development., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objectives: To review evidence about the uptake of core outcome sets (COS). A COS is an agreed standardized set of outcomes that should be measured and reported, as a minimum, in all clinical trials in a specific area of health or healthcare., Study Design and Setting: This article provides an analysis of what is known about the uptake of COS in research. Similarities between COS and outcomes recommended by stakeholders in the evidence ecosystem is reviewed and actions taken by them to facilitate COS uptake described., Results: COS uptake is low in most research areas. Common facilitators relate to trialist awareness and understanding. Common barriers were not including in the development process all specialties that might use the COS and the lack of recommendations for how to measure the outcomes. Increasingly, COS developers are considering strategies for promoting uptake earlier in the process, including actions beyond traditional dissemination approaches. An overlap between COS and outcomes in regulatory documents and health technology assessments is good. An increasing number and variety of organizations are recommending COS be considered., Conclusion: We suggest actions for various stakeholders for improving COS uptake. Research is needed to assess the impact of these actions to identify effective evidence-based strategies., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objective: Our study aims to describe differences or similarities in the scope, participant characteristics and methods used in core outcome sets (COS) development when only participants from high-income countries (HICs) were involved compared with when participants from low-income and middle-income countries (LMICs) were also involved., Design: Systematic review., Data Sources: Annual Core Outcome Measures in Effectiveness Trials systematic reviews of COS which are updated based on SCOPUS and MEDLINE, searches. The latest systematic review included studies published up to the end of 2019., Eligibility Criteria for Selecting Studies: We included studies reporting development of a COS for use in research regardless of age, health condition or setting. Studies reporting the development of a COS for patient-reported outcomes or adverse events or complications were also included., Data Extraction and Synthesis: Data were extracted in relation to scope of the COS study, participant categories and the methods used in outcome selection., Results: Studies describing 370 COS were identified in the database. Of these, 75 (20%) included participants from LMICs. Only four COS were initiated from an LMIC setting. More than half of COS with LMIC participants were developed in the last 5 years. Cancer and rheumatology were the dominant disease domains. Overall, over 259 (70%) of COS explicitly reported including clinical experts; this was higher where LMIC participants were also included 340 (92%). Most LMIC participants were from China, Brazil and South Africa. Mixed methods for consensus building were used across the two settings., Conclusion: Progress has been made in including LMIC participants in the development of COS, however, there is a need to explore how to enable initiation of COS development from a range of LMIC settings, how to ensure prioritisation of COS that better reflects the burden of disease in these contexts and how to improve public participation from LMICs., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY. Published by BMJ.)

Background: An annual update to a systematic review of core outcome sets (COS) for research ensures that the COMET database is up-to-date. The aims of this study were to: (i) identify COS that were published or indexed in 2019 and to describe the methodological approaches used in these studies; (ii) investigate whether children have been included as participants in published COS development studies, and which methods have been used to facilitate their participation; iii) update a previous exercise to identify COS relevant to the most burdensome global diseases and injuries., Methods: MEDLINE and SCOPUS were searched to identify studies published or indexed between (and inclusive of) January 2019 and December 2019. Automated screening methods were used to rank the citations in order of relevance; the top 25% in ranked priority order were screened for eligibility. COS were assessed against each of the Core Outcome Set-STAndards for Development (COS-STAD). A search of the COMET database was undertaken to identify COS relevant to the 25 leading causes of disease burden., Results: Thirty-three studies, describing the development of 37 COS, were included in this update. These studies have been added to the COMET database, which now contains 370 published (1981-2019) COS studies for clinical research. Six (18%) of the 33 studies in this update were deemed to have met all of the minimum standards for COS development (range = 4 to 12 criteria, median = 9 criteria). Of the 370 COS studies published to date, 82 COS have been developed for paediatric health conditions and children would have been eligible to participate in 68/82 of these studies. Eleven of these 68 (16%) COS studies have included children as participants within the development process, most commonly through participation in Delphi surveys. Relevant COS were identified for 22/25 leading causes of global disease burden., Conclusion: There has been a demonstrated increase in COS developed for both research and routine practice, and consistently high inclusion of patient participants. COS developed for paediatric conditions need to further incorporate the perspectives of children, alongside parents and other adults, and adopt research methods fit for this purpose. COS developers should consider the gaps identified in this update as priorities for COS development., Competing Interests: EG and PRW are members of the COMET Management Group. SLG and KMS have declared that no competing interests exist. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Evaluation studies of outcomes used in clinical research and their consistency are appearing more frequently in the literature, as a key part of the core outcome set (COS) development. Current guidance suggests such evaluation studies should use systematic review methodology as their default. We aimed to examine the methods used. We searched the Core Outcome Measures in Effectiveness Trials (COMET) database (up to May 2019) supplementing it with additional resources. We included evaluation studies of outcome consistency in clinical studies across health subjects and used a subset of A MeaSurement Tool to Assess systematic Reviews (AMSTAR) 2 (items 1-9) to assess their methods. Of 93 included evaluation studies of outcome consistency (90 full reports, three summaries), 91% (85/93) reported performing literature searches in at least one bibliographic database, and 79% (73/93) was labelled as a "systematic review". The evaluations varied in terms of satisfying AMSTAR 2 criteria, such that 81/93 (87%) had implemented PICO in the research question, whereas only 5/93 (6%) had included the exclusions list. None of the evaluation studies explained how inconsistency of outcomes was detected, however, 80/90 (88%) concluded inconsistency in individual outcomes (66%, 55/90) or outcome domains (20%, 18/90). Methods used in evaluation studies of outcome consistency in clinical studies differed considerably. Despite frequent being labelled as a "systematic review", adoption of systematic review methodology is selective. While the impact on COS development is unknown, authors of these studies should refrain from labelling them as "systematic review" and focus on ensuring that the methods used to generate the different outcomes and outcome domains are reported transparently., Competing Interests: The authors have declared that no competing interests exist.

Background: A systematic review of core outcome sets (COS) for research is updated annually to populate an online database. It is a resource intensive review to do annually but automation techniques have potential to aid the process. The production of guidance and standards in COS development means that there is now an expectation that COS are being developed and reported to a higher standard. This is the fifth update to the systematic review and will explore these issues., Methods: Searches were carried out to identify studies published or indexed in 2018. Automated screening methods were used to rank the citations in order of relevance. The cut-off for screening was set to the top 25% in ranked priority order, following development and validation of the algorithm. Studies were eligible for inclusion if they reported the development of a COS, regardless of any restrictions by age, health condition or setting. COS were assessed against each of the Core Outcome Set-STAndards for Development (COS-STAD)., Results: Thirty studies describing the development of 44 COS were included in this update. Six COS (20%) were deemed to have met all 12 criteria representing the 11 minimum standards for COS development (range = 4 to 12 criteria, median = 10 criteria). All 30 COS studies met all four minimum standards for scope. Twenty-one (70%) COS met all three minimum standards for stakeholders. Twenty-three studies (77%) included patients with the condition or their representatives. The number of countries involved in the development of COS ranged from 1 to 39 (median = 10). Six studies (20%) met all four minimum standards [five criteria] for the consensus process., Conclusion: Automated ranking was successfully used to assist the screening process and reduce the workload of this systematic review update. With the provision of guidelines, COS are better reported and being developed to a higher standard., Competing Interests: EG and PW are members of the COMET Management Group. All other authors had no competing interests. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Objective: Establishing a research agenda on standardizing pain measurement in clinical trials in rheumatic and musculoskeletal diseases (RMD)., Methods: Discussion during a meeting at the Outcome Measures in Rheumatology (OMERACT) 2018, prepared by a systematic review of existing core outcome sets and a patient online survey., Results: Several key questions were debated: Is pain a symptom or a disease? Are pain core (sub)domains consistent across RMD? How to account for pain mechanistic descriptors (e.g., central sensitization) in pain measurement?, Conclusion: Characterizing and assessing the spectrum of pain experience across RMD in a standardized fashion is the objective of the OMERACT Pain Working Group.

Objective: The Core Outcome Set-STAndards for Development (COS-STAD) contains 11 standards (12 criteria) that are deemed to be the minimum design recommendations for all core outcome set (COS) development projects. Cancer is currently the disease area with the highest number of published COSs and is a major cause of worldwide morbidity and mortality. The aim of this study was to provide a baseline of cancer COS standards., Study Design and Setting: Systematic reviews of COSs have identified 307 published COS studies. Cancer COSs were eligible for inclusion. Two reviewers independently assessed each of the COSs against the 12 criteria., Results: Forty-nine cancer COSs were included; none met all 12 criteria representing the 11 minimum standards assessed in this study (range = 4-11 criteria, median = 6 criteria). All studies met the four scope standards, eight (16%) met all three standards for stakeholders involved, and two (4%) met all four standards for consensus process standards., Conclusion: With the exception of "scope" specification, there is much need for improvement. Poor reporting often made it challenging to assess whether minimum standards were met. The consensus process criteria were most difficult to assess, particularly those that required an assessment of being a priori. This is the first application of COS-STAD criteria to studies that have developed COSs and provides a baseline of cancer COS standards of development., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: The Delphi method is commonly used to achieve consensus in core outcome set (COS) development. It is important to try to maximize response rates to Delphi studies and minimize attrition rates and potential for bias. The factors that impact response rates in a Delphi study used for COS development are unknown. The objective of this study was to explore the impact of design characteristics on response rates in Delphi surveys within COS development., Methods: Published and ongoing studies that included Delphi to develop a COS were eligible. Second round voting response rates were analyzed, and multilevel linear regression was conducted to investigate whether design characteristics were associated with the response rate., Results: Thirty-one studies were included. Two characteristics were significantly associated with a lower response rate: larger panels and studies with more items included., Conclusion: COS developers should pay attention to methods when designing a COS development study; in particular, the size of the panels and the size of the list of outcomes. We identified other potential design characteristics that might influence response rates but were unable to explore them in this analysis. These should be reported in future reports to allow for further investigation., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Curated databases of scientific literature play an important role in helping researchers find relevant literature, but populating such databases is a labour intensive and time-consuming process. One such database is the freely accessible Comet Core Outcome Set database, which was originally populated using manual screening in an annually updated systematic review. In order to reduce the workload and facilitate more timely updates we are evaluating machine learning methods to reduce the number of references needed to screen. In this study we have evaluated a machine learning approach based on logistic regression to automatically rank the candidate articles. Data from the original systematic review and its four first review updates were used to train the model and evaluate performance. We estimated that using automatic screening would yield a workload reduction of at least 75% while keeping the number of missed references around 2%. We judged this to be an acceptable trade-off for this systematic review, and the method is now being used for the next round of the Comet database update., (© The Author(s) 2019. Published by Oxford University Press.)

Background: The Core Outcome Measures in Effectiveness Trials (COMET) database is a publically available, searchable repository of published and ongoing core outcome set (COS) studies. An annual systematic review update is carried out to maintain the currency of database content., Methods: The methods used in the fourth update of the systematic review followed the same approach used in the original review and previous updates. Studies were eligible for inclusion if they reported the development of a COS, regardless of any restrictions by age, health condition or setting. Searches were carried out in March 2018 to identify studies that had been published or indexed between January 2017 and the end of December 2017., Results: Forty-eight new studies, describing the development of 56 COS, were included. There has been an increase in the number of studies clearly specifying the scope of the COS in terms of the population (n = 43, 90%) and intervention (n = 48, 100%) characteristics. Public participation has continued to rise with over half (n = 27, 56%) of studies in the current review including input from members of the public. The rate of inclusion of all stakeholder groups has increased, in particular participation from non-clinical research experts has risen from 32% (mean average in previous reviews) to 62% (n = 29). Input from participants located in Australasia (n = 17; 41%), Asia (n = 18; 44%), South America (n = 13; 32%) and Africa (n = 7; 17%) have all increased since the previous reviews., Conclusion: This update included a pronounced increase in the number of new COS identified compared to the previous three updates. There was an improvement in the reporting of the scope, stakeholder participants and methods used. Furthermore, there has been an increase in participation from Australasia, Asia, South America and Africa. These advancements are reflective of the efforts made in recent years to raise awareness about the need for COS development and uptake, as well as developments in COS methodology., Competing Interests: EG and PW are members of the COMET Management Group. All other authors had no competing interests. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Background: Core outcome sets (COS) comprise a minimum set of outcomes that should be measured and reported in all trials for a specific health condition. The COMET (Core Outcome Measures in Effectiveness Trials) Initiative maintains an up to date, publicly accessible online database of published and ongoing COS. An annual systematic review update is an important part of this process., Methods: This review employed the same, multifaceted approach that was used in the original review and the previous two updates. This approach has identified studies that sought to determine which outcomes/domains to measure in clinical trials of a specific condition. This update includes an analysis of the inclusion of participants from low and middle income countries (LMICs) as identified by the OECD, in these COS., Results: Eighteen publications, relating to 15 new studies describing the development of 15 COS, were eligible for inclusion in the review. Results show an increase in the use of mixed methods, including Delphi surveys. Clinical experts remain the most common stakeholder group involved. Overall, only 16% of the 259 COS studies published up to the end of 2016 have included participants from LMICs., Conclusion: This review highlights opportunities for greater public participation in COS development and the involvement of stakeholders from a wider range of geographical settings, in particular LMICs.

The selection of appropriate outcomes is crucial when designing clinical trials in order to compare the effects of different interventions directly. For the findings to influence policy and practice, the outcomes need to be relevant and important to key stakeholders including patients and the public, health care professionals and others making decisions about health care. It is now widely acknowledged that insufficient attention has been paid to the choice of outcomes measured in clinical trials. Researchers are increasingly addressing this issue through the development and use of a core outcome set, an agreed standardised collection of outcomes which should be measured and reported, as a minimum, in all trials for a specific clinical area.Accumulating work in this area has identified the need for guidance on the development, implementation, evaluation and updating of core outcome sets. This Handbook, developed by the COMET Initiative, brings together current thinking and methodological research regarding those issues. We recommend a four-step process to develop a core outcome set. The aim is to update the contents of the Handbook as further research is identified.

Objectives: The objective of the study was to explore core outcome set (COS) developers' experiences of their work to inform methodological guidance on COS development and identify areas for future methodological research., Study Design and Setting: Semistructured, audio-recorded interviews with a purposive sample of 32 COS developers. Analysis of transcribed interviews was informed by the constant comparative method and framework analysis., Results: Developers found COS development to be challenging, particularly in relation to patient participation and accessing funding. Their accounts raised fundamental questions about the status of COS development and whether it is consultation or research. Developers emphasized how the absence of guidance had affected their work and identified areas where guidance or evidence about COS development would be useful including, patient participation, ethics, international development, and implementation. They particularly wanted guidance on systematic reviews, Delphi, and consensus meetings., Conclusion: The findings raise important questions about the funding, status, and process of COS development and indicate ways that it could be strengthened. Guidance could help developers to strengthen their work, but over specification could threaten quality in COS development. Guidance should therefore highlight common issues to consider and encourage tailoring of COS development to the context and circumstances of particular COS., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: The COMET (Core Outcome Measures in Effectiveness Trials) Initiative promotes the development and application of core outcome sets (COS), including relevant studies in an online database. In order to keep the database current, an annual search of the literature is undertaken. This study aimed to update a previous systematic review, in order to identify any further studies where a COS has been developed. Furthermore, no prioritization for COS development has previously been undertaken, therefore this study also aimed to identify COS relevant to the world's most prevalent health conditions., Methods: The methods used in this updated review followed the same approach used in the original review and the previous update. A survey was also sent to the corresponding authors of COS identified for inclusion in this review, to ascertain what lessons they had learnt from developing their COS. Additionally, the COMET database was searched to identify COS that might be relevant to the conditions with the highest global prevalence., Results: Twenty-five reports relating to 22 new studies were eligible for inclusion in the review. Further improvements were identified in relation to the description of the scope of the COS, use of the Delphi technique, and the inclusion of patient participants within the development process. Additionally, 33 published and ongoing COS were identified for 13 of the world's most prevalent conditions., Conclusion: The development of a reporting guideline and minimum standards should contribute towards future improvements in development and reporting of COS. This study has also described a first approach to identifying gaps in existing COS, and to priority setting in this area. Important gaps have been identified, on the basis of global burden of disease, and the development and application of COS in these areas should be considered a priority., Competing Interests: MC and PRW are members of the COMET Management Group and coapplicants on grants to support COMET and related work. EG is a member of the COMET Management Group and is the COMET Project Co-ordinator. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.

Background: Core outcome sets (COS) can enhance the relevance of research by ensuring that outcomes of importance to health service users and other people making choices about health care in a particular topic area are measured routinely. Over 200 COS to date have been developed, but the clarity of these reports is suboptimal. COS studies will not achieve their goal if reports of COS are not complete and transparent., Methods and Findings: In recognition of these issues, an international group that included experienced COS developers, methodologists, journal editors, potential users of COS (clinical trialists, systematic reviewers, and clinical guideline developers), and patient representatives developed the Core Outcome Set-STAndards for Reporting (COS-STAR) Statement as a reporting guideline for COS studies. The developmental process consisted of an initial reporting item generation stage and a two-round Delphi survey involving nearly 200 participants representing key stakeholder groups, followed by a consensus meeting. The COS-STAR Statement consists of a checklist of 18 items considered essential for transparent and complete reporting in all COS studies. The checklist items focus on the introduction, methods, results, and discussion section of a manuscript describing the development of a particular COS. A limitation of the COS-STAR Statement is that it was developed without representative views of low- and middle-income countries. COS have equal relevance to studies conducted in these areas, and, subsequently, this guideline may need to evolve over time to encompass any additional challenges from developing COS in these areas., Conclusions: With many ongoing COS studies underway, the COS-STAR Statement should be a helpful resource to improve the reporting of COS studies for the benefit of all COS users., Competing Interests: I have read the journal's policy and have the following conflicts: DGA, JMB, MC, EG, PRW, and ST are members of the COMET Management Group. DM is a member of the Editorial Board of PLOS Medicine. DD, SG, JJK, JS, and PT declare no competing interests.

Policy makers have clearly indicated--through heavy investment in the Patient Centered Outcomes Research Institute--that reporting outcomes that are meaningful to patients is crucial for improvement in healthcare delivery and cost reduction. Better interpretation and generalizability of clinical research results that incorporate patient-centered outcomes research can be achieved by accelerating the development and uptake of core outcome sets (COS). COS provide a standardized minimum set of the outcomes that should be measured and reported in all clinical trials of a specific condition. The level of activity around COS has increased significantly over the past decade, with substantial progress in several clinical domains. However, there are many important clinical conditions for which high-quality COS have not been developed and there are limited resources and capacity with which to develop them. We believe that meaningful progress toward the goals behind the significant investments in patient-centered outcomes research and comparative effectiveness research will depend on a serious effort to address these issues., Competing Interests: Financial & competing interests disclosure This work was supported in part by a Eugene Washington Engagement Award from the Patient Centered Outcomes Research Institute. This work was also funded in part by the MRC MRP (Medical Research Council Methodology Research Panel), grant number MR/J004847/1; and European Union Seventh Framework Programme ([FP7/2007-2013] [FP7/2007-2011]) under grant agreement number 305081. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.

Background: A COS represents an agreed minimum set of outcomes that should be measured and reported in all trials of a specific condition. The COMET (Core Outcome Measures in Effectiveness Trials) initiative aims to collate and stimulate the development and application of COS, by including data on relevant studies within a publically available internet-based resource. In recent years, there has been an interest in increasing the development of COS. Therefore, this study aimed to provide an update of a previous review, and examine the quality of development of COS. A further aim was to understand the reasons why individuals are searching the COMET database., Methods: A multi-faceted search strategy was followed, in order to identify studies that sought to determine which outcomes/domains to measure in clinical trials of a specific condition. Additionally, a pop up survey was added to the COMET website, to ascertain why people were searching the COMET database., Results: Thirty-two reports relating to 29 studies were eligible for inclusion in the review. There has been an improvement in the description of the scope of a COS and an increase in the proportion of studies using literature/systematic reviews and the Delphi technique. Clinical experts continue to be the most common group involved in developing COS, however patient and public involvement has increased. The pop-up survey revealed the most common reasons for visiting the COMET website to be thinking about developing a COS and planning a clinical trial., Conclusions: This update demonstrates that recent studies appear to have adopted a more structured approach towards COS development and public representation has increased. However, there remains a need for developers to adequately describe details about the scope of COS, and for greater public engagement. The COMET database appears to be a useful resource for both COS developers and users of COS.

Background: Core outcome sets can increase the efficiency and value of research and, as a result, there are an increasing number of studies looking to develop core outcome sets (COS). However, the credibility of a COS depends on both the use of sound methodology in its development and clear and transparent reporting of the processes adopted. To date there is no reporting guideline for reporting COS studies. The aim of this programme of research is to develop a reporting guideline for studies developing COS and to highlight some of the important methodological considerations in the process., Methods/design: The study will include a reporting guideline item generation stage which will then be used in a Delphi study. The Delphi study is anticipated to include two rounds. The first round will ask stakeholders to score the items listed and to add any new items they think are relevant. In the second round of the process, participants will be shown the distribution of scores for all stakeholder groups separately and asked to re-score. A final consensus meeting will be held with an expert panel and stakeholder representatives to review the guideline item list. Following the consensus meeting, a reporting guideline will be drafted and review and testing will be undertaken until the guideline is finalised. The final outcome will be the COS-STAR (Core Outcome Set-STAndards for Reporting) guideline for studies developing COS and a supporting explanatory document., Discussion: To assess the credibility and usefulness of a COS, readers of a COS development report need complete, clear and transparent information on its methodology and proposed core set of outcomes. The COS-STAR guideline will potentially benefit all stakeholders in COS development: COS developers, COS users, e.g. trialists and systematic reviewers, journal editors, policy-makers and patient groups.

Background: A core outcome set (COS) can address problems of outcome heterogeneity and outcome reporting bias in trials and systematic reviews, including Cochrane reviews, helping to reduce waste. One of the aims of the international Core Outcome Measures in Effectiveness Trials (COMET) Initiative is to link the development and use of COS with the outcomes specified and reported in Cochrane reviews, including the outcomes listed in the summary of findings (SoF) tables. As part of this work, an earlier exploratory survey of the outcomes of newly published 2007 and 2011 Cochrane reviews was performed. This survey examined the use of COS, the variety of specified outcomes, and outcome reporting in Cochrane reviews by Cochrane Review Group (CRG). To examine changes over time and to explore outcomes that were repeatedly specified over time in Cochrane reviews by CRG, we conducted a follow-up survey of outcomes in 2013 Cochrane reviews., Methods: A descriptive survey of outcomes in Cochrane reviews that were first published in 2013. Outcomes specified in the methods sections and reported in the results section of the Cochrane reviews were examined by CRG. We also explored the uptake of SoF tables, the number of outcomes included in these, and the quality of the evidence for the outcomes., Results: Across the 50 CRGs, 375 Cochrane reviews that included at least one study specified a total of 3142 outcomes. Of these outcomes, 32 % (1008) were not reported in the results section of these reviews. For 23 % (233) of these non-reported outcomes, we did not find any reason in the text of the review for this non-report. Fifty-seven percent (216/375) of reviews included a SoF table., Conclusions: The proportion of specified outcomes that were reported in Cochrane reviews had increased in 2013 (68 %) compared to 2007 (61 %) and 2011 (65 %). Importantly, 2013 Cochrane reviews that did not report specified outcomes were twice as likely to provide an explanation for why the outcome was not reported. There has been an increased uptake of SoF tables in Cochrane reviews. Outcomes that were repeatedly specified in Cochrane reviews by CRG in 2007, 2011, and 2013 may assist COS development.

Background: The COMET (Core Outcome Measures in Effectiveness Trials) Initiative is developing a publicly accessible online resource to collate the knowledge base for core outcome set development (COS) and the applied work from different health conditions. Ensuring that the database is as comprehensive as possible and keeping it up to date are key to its value for users. This requires the development and application of an optimal, multi-faceted search strategy to identify relevant material. This paper describes the challenges of designing and implementing such a search, outlining the development of the search strategy for studies of COS development, and, in turn, the process for establishing a database of COS., Methods: We investigated the performance characteristics of this strategy including sensitivity, precision and numbers needed to read. We compared the contribution of databases towards identifying included studies to identify the best combination of methods to retrieve all included studies., Results: Recall of the search strategies ranged from 4% to 87%, and precision from 0.77% to 1.13%. MEDLINE performed best in terms of recall, retrieving 216 (87%) of the 250 included records, followed by Scopus (44%). The Cochrane Methodology Register found just 4% of the included records. MEDLINE was also the database with the highest precision. The number needed to read varied between 89 (MEDLINE) and 130 (SCOPUS)., Conclusions: We found that two databases and hand searching were required to locate all of the studies in this review. MEDLINE alone retrieved 87% of the included studies, but actually 97% of the included studies were indexed on MEDLINE. The Cochrane Methodology Register did not contribute any records that were not found in the other databases, and will not be included in our future searches to identify studies developing COS. SCOPUS had the lowest precision rate (0.77) and highest number needed to read (130). In future COMET searches for COS a balance needs to be struck between the work involved in screening large numbers of records, the frequency of the searching and the likelihood that eligible studies will be identified by means other than the database searches.

Objectives: To survey the outcomes used in Cochrane Reviews, as part of our work within the Core Outcome Measures in Effectiveness Trials Initiative., Study Design and Setting: A descriptive survey of Cochrane Reviews, divided by Cochrane Review Group (CRG), published in full for the first time in 2007 and 2011. Outcomes specified in the methods section of each review and outcomes reported in the results section of each review were of interest, in this exploration of the common use of outcomes and core outcome sets (COS)., Results: Seven hundred eighty-eight reviews, specifying 6,127 outcomes, were included. When we excluded specified outcomes from the 86 reviews that did not include any studies, we found that 1,996 (37%) specified outcomes were not reported. Of the 361 new reviews with studies from 2011, 113 (31%) had a "summary of findings" table (SoF). Fifteen broad outcome categories were identified and used to manage the outcome data. We found consistency in the use of these categories across CRGs but inconsistency in outcomes within these categories., Conclusion: COS have been used rarely in Cochrane Reviews, but the introduction of SoF makes the development and application of COS timelier than ever., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: A core outcome set (COS) is a standardised set of outcomes which should be measured and reported, as a minimum, in all effectiveness trials for a specific health area. This will allow results of studies to be compared, contrasted and combined as appropriate, as well as ensuring that all trials contribute usable information. The COMET (Core Outcome Measures for Effectiveness Trials) Initiative aims to support the development, reporting and adoption of COS. Central to this is a publically accessible online resource, populated with all available COS. The aim of the review we report here was to identify studies that sought to determine which outcomes or domains to measure in all clinical trials in a specific condition and to describe the methodological techniques used in these studies., Methods: We developed a multi-faceted search strategy for electronic databases (MEDLINE, SCOPUS, and Cochrane Methodology Register). We included studies that sought to determine which outcomes/domains to measure in all clinical trials in a specific condition., Results: A total of 250 reports relating to 198 studies were judged eligible for inclusion in the review. Studies covered various areas of health, most commonly cancer, rheumatology, neurology, heart and circulation, and dentistry and oral health. A variety of methods have been used to develop COS, including semi-structured discussion, unstructured group discussion, the Delphi Technique, Consensus Development Conference, surveys and Nominal Group Technique. The most common groups involved were clinical experts and non-clinical research experts. Thirty-one (16%) studies reported that the public had been involved in the process. The geographic locations of participants were predominantly North America (n = 164; 83%) and Europe (n = 150; 76%)., Conclusions: This systematic review identified many health areas where a COS has been developed, but also highlights important gaps. It is a further step towards a comprehensive, up-to-date database of COS. In addition, it shows the need for methodological guidance, including how to engage key stakeholder groups, particularly members of the public.

Background: Symptom measurement in pediatric chronic idiopathic constipation (CIC) and irritable bowel syndrome with constipation (IBS-C) trials requires appropriately developed clinical outcome assessments (COAs)., Methods: Literature was reviewed to identify symptom COAs meeting regulatory standards. Searches were conducted in Pubmed/Medline, EMBASE, and PsychINFO. Title/abstracts were reviewed to identify qualitative studies and those using COAs to measure pediatric CIC/IBS symptoms. Pediatric functional gastrointestinal experts provided input on relevant symptom-concepts to measure., Results: Review of 1,105 abstracts identified 1 relevant qualitative article and 113 articles including COAs. Symptoms most frequently measured in CIC studies were frequency of bowel movements, fecal incontinence/encopresis, abdominal pain, stool consistency, and painful defecation. Symptoms most frequently measured in IBS were abdominal pain, abdominal distention/bloating, stool consistency, frequency of bowel movements, and gas. Evidence of development/validity of COAs was limited. Expert feedback was broadly consistent with the literature., Conclusion: Findings demonstrate consistency in the literature on key CIC/IBS symptoms to measure in pediatric trials, but existing COAs do not meet regulatory standards.

Background: Adverse drug reactions in children are an important public health problem. We have undertaken a systematic review of observational studies in children in three settings: causing admission to hospital, occurring during hospital stay and occurring in the community. We were particularly interested in understanding how ADRs might be better detected, assessed and avoided., Methods and Findings: We searched nineteen electronic databases using a comprehensive search strategy. In total, 102 studies were included. The primary outcome was any clinical event described as an adverse drug reaction to one or more drugs. Additional information relating to the ADR was collected: associated drug classification; clinical presentation; associated risk factors; methods used for assessing causality, severity, and avoidability. Seventy one percent (72/102) of studies assessed causality, and thirty four percent (34/102) performed a severity assessment. Only nineteen studies (19%) assessed avoidability. Incidence rates for ADRs causing hospital admission ranged from 0.4% to 10.3% of all children (pooled estimate of 2.9% (2.6%, 3.1%)) and from 0.6% to 16.8% of all children exposed to a drug during hospital stay. Anti-infectives and anti-epileptics were the most frequently reported therapeutic class associated with ADRs in children admitted to hospital (17 studies; 12 studies respectively) and children in hospital (24 studies; 14 studies respectively), while anti-infectives and non-steroidal anti-inflammatory drugs (NSAIDs) were frequently reported as associated with ADRs in outpatient children (13 studies; 6 studies respectively). Fourteen studies reported rates ranging from 7%-98% of ADRs being either definitely/possibly avoidable., Conclusions: There is extensive literature which investigates ADRs in children. Although these studies provide estimates of incidence in different settings and some indication of the therapeutic classes most frequently associated with ADRs, further work is needed to address how such ADRs may be prevented.