A core outcome set and reporting checklist for research on critically ill obstetric patients: An international consensus study

INTRODUCTION Our objective was to develop a Core Outcome Set for Research on Critically Ill Obstetric Patients (COSCO) through international consensus, with the aim of improving consistency, comparability, and clinical relevance across studies involving this population.

MATERIAL AND METHODS This international, multi-method study was conducted between February 16, 2023, and January 18, 2024. The process included a two-round online Delphi survey, three small group discussions, and a final consensus meeting. Participants comprised health service users (HSUs) with lived experience of critical illness during pregnancy and healthcare professionals from diverse specialties and geographic regions.

RESULTS Sixty-eight participants (11 HSUs and 57 healthcare professionals) from 16 countries scored 23 candidate items identified through a systematic review and qualitative interviews. Through consensus, 10 core outcomes and 7 reporting checklist items were selected for inclusion in all research on critical illness in obstetrics. Core outcomes included maternal all-cause mortality; cardiac arrest and the need for cardiopulmonary resuscitation (not resulting in death); severe (maternal) organ dysfunction; length of stay in the intensive care unit (ICU) and total hospital stay; readmission to hospital or ICU or repeated hospital/emergency department visits following discharge from ICU; presence of a new medical condition at the time of discharge from hospital, which was not present at the time of admission to the hospital; permanent infertility as a consequence of critical illness or intervention; perinatal loss; severe neonatal morbidity requiring prolonged neonatal ICU admission; and gestational age/preterm birth. Four additional noncore outcomes were identified as important but may be challenging to measure consistently; these should be reported when relevant and feasible.

CONCLUSIONS COSCO provides a standardized, consensus-based framework for outcome reporting in research on critically ill obstetric patients. Its adoption will strengthen methodological rigor, reduce reporting heterogeneity, enhance comparability across studies, and support evidence-based, patient-centered guideline development.