Introduction

A core outcome set (COS) represents an agreed set of outcomes that should be measured and reported, as a minimum, in all clinical trials in a specific area of health or health care,1 and can be used in other research and clinical audit.2 COS development and implementation is supported by the Core Outcome Measures in Effectiveness Trials (COMET) Initiative. Launched in 2010, COMET collates and stimulates the development and application of agreed standardised COS by maintaining a publicly available, searchable database of published and ongoing COS.3 The Core Outcomes in Women’s and Newborn Health (CROWN) Initiative strongly supports the development and dissemination of COS within women’s health research.4
With over 330 published COS developed in several health disciplines since 1981,5 COS related to maternal and neonatal care has seen slower development. In a 2017 systematic review, Duffy and colleagues identified only four published COS related to women’s and newborn health, three of which related to pregnancy and childbirth.6 To be effective, COS must be developed using rigorous methods that reflect outcomes important to patients and other stakeholders.7 The recent minimum standards for COS development (Core Outcome Set-STAndards for Development: COS-STAD) facilitates the assessment of whether a COS has been developed using a reasonable approach.8 Core outcome set methodology is however in its infancy, and advancements in methodologic standards are likely in the future.9 To evaluate progress, a baseline of methodological rigor is required to inform future maternal and neonatal COS development.
To date, little attention has been paid to the harmonisation of outcomes between similar COS. Without harmonisation of definitions, measures and timing, there is a danger that heterogeneity and research wastage will continue. The aim of the current study was to evaluate maternal and neonatal COS against available standards of development. The current study is guided by the following research questions:
  1. Do existing completed maternal and neonatal core outcome sets meet minimum standards for development?
  2. What is the extent of concordance between core outcome sets?