Development of an international core outcome set for treatment trials in paediatric inguinal hernia: protocol for a three-phase study including a systematic review and Delphi survey.

Introduction: In children, open inguinal hernia repair has been the gold standard for treatment, but with recent technical advancements in laparoscopy, laparoscopic hernia repair is gaining popularity. Despite available results from comparative studies, there is still no consensus regarding the superiority of open versus laparoscopic treatment strategy. An important reason for lack of consensus is the large heterogeneity in the trials' reported outcomes and outcome definitions, which limits comparisons between studies and precludes conclusions regarding the superiority of treatment strategies. The development and implementation of a core outcome set (COS) is a solution for this heterogeneity in the selection, measurement and reporting of trial outcome measures across studies. Currently, there is no COS for the treatment of paediatric inguinal hernia.

Methods And Analysis: The aim of this project is to reach international consensus on a minimal set of outcomes that should be measured and reported in all future clinical trials investigating inguinal hernia repair in children. The development process comprises three phases. First, we identify outcome domains associated with paediatric inguinal hernia repair from a patient perspective and through a systematic review of the literature using EMBASE, MEDLINE and the Cochrane Library databases. Second, we conduct a three-step Delphi study to identify and prioritise 'core' outcomes for the eventual minimal set. In the third phase, an expert meeting is held to establish the final COS and develop implementation strategies with participants from all stakeholder groups: healthcare professionals, parents and patients' representatives. The final COS will be reported in accordance with the COS-Standards for Reporting statement.

Ethics And Dissemination: The medical research ethics committee of the Amsterdam UMC confirmed that the Dutch Medical Research Involving Human Subjects Act (WMO) does not apply to this study and that full approval by the committee is not required. Electronic informed consent will be obtained from all participants. Results will be presented in peer-reviewed academic journals and at relevant conferences.

Prospero Registration Number: CRD42021281422.