Core outcome set for uncomplicated acute appendicitis in children and young people

Introduction
Selection of outcomes that are important to patients as well as to health professionals is essential if studies are to inform policy and practice. Consistent selection of outcomes across studies aids comparison and combination of results. These can both be achieved by using core outcome sets. We aimed to develop a core outcome set for uncomplicated acute appendicitis in children and young people.

Methods
Systematic literature reviews, qualitative interviews with parents and patients treated for uncomplicated acute appendicitis, and a Study-Specific Advisory Group informed a long list of outcomes. Outcomes were then prioritised by stakeholders based in the United Kingdom (patients, parents, and paediatric and general surgeons) in an online three-round Delphi consensus process, followed by face-to-face consensus meetings.

Results
A long list of 40 items was scored by 147 key stakeholders in the first Delphi round, of whom 90 completed the two subsequent Delphi rounds. The final core outcome set comprises 14 outcomes: intra-abdominal abscess, re-operation (including interventional radiology procedure), readmission, bowel obstruction, wound infection, other wound complication, antibiotic failure, negative appendicectomy, recurrent appendicitis, death, patient stress/psychological distress, length of hospital stay, time away from full activities and quality of life.

Discussion
We used established consensus methods to develop a core outcome set for uncomplicated acute appendicitis in children. The core outcome set should be adopted by researchers to report outcomes of uncomplicated acute appendicitis in children in order to enhance the quality of research and facilitate comparison between trials. Further work will determine how and when to measure these outcomes.