INTRODUCTION
Clinical trials are undertaken in a range of settings and populations to support evidence-based practice.(1) The reporting of standardised outcome measures facilitates comparisons between trials.(2) Outcome selection however varies widely between trials and few outcomes reflect the perspectives of and are directly relevant to trial participants.(3) The development of Core Outcome Sets (COS) has been encouraged to address these issues, identifying minimum outcomes recommended for routine measurement and reporting in clinical trials and systematic reviews in shared areas, whilst allowing researchers to add further outcomes to address specific questions.(2) Core outcome sets include outcomes, or domains, to be measured in clinical trials, and recommendations for which instruments should be used, and when, to quantify domains.(4, 5)
The Core Outcome Measures for Effectiveness Trials (COMET) initiative, established in 2010, supports COS developers by providing methodological guidelines and hosting a repository of COS studies.(6-8) Guidelines recommend consensus science methods engaging diverse stakeholders including health professionals, researchers and patients, aiming to improve the inclusion of patient centred outcomes, reduce selective outcome reporting and facilitate prospective analysis.(2, 9, 10) The process typically involves 6 stages: (1) defining COS scope (2) COMET registration, avoiding duplication (3) protocol development (4) systematic review of outcome measures followed by Delphi process to refine core outcomes (5) implementation.
Over 80 specialty journals, including BJOG: An InternationalJournal of Obstetrics and Gynaecology , have come together within the Core Outcomes in Women’s and Newborn Health (CROWN) initiative to support researchers to develop, disseminate, and implement COS.(11, 12) As interest has grown in this area, variable quality has been noted in the development and reporting of COS.(9) In response, standards have been developed through Delphi processes with COS developers, journal editors and patient and public representatives. These propose minimum expectations for methodological and reporting quality for COS, promoting research integrity and transparency.(13) The Core Outcome Set-STAndardised Protocol (COS-STAP) specify protocol methods,(13) the Core Outcome Set STAndards for Development (COS-STAD) identifies methodological standards,(14) and the Core Outcome Set STAndards for Reporting (COS-STAR) identifies reporting standards of completed COS.(15)
A review of the COMET and CROWN databases in 2017 identified COS development studies relevant to women’s and newborn health.(11) Since then, there has been rapid expansion of the COMET database and the introduction of quality standards.(13-15) The aim of this study was to review women’s and newborn health COS registered with the COMET or CROWN initiative, evaluate methodological and reporting quality and consider how COS development may be improved.