International Core Outcome Set for Acute Simple Appendicitis in Children: Results of a Systematic Review, Delphi Study, and Focus Croups with Young People

Max Knaapen, Nigel J. Hall, Darcy Moulin, Johanna H. van der Lee, Nancy J. Butcher, Peter C. Minneci, Jan F. Svensson, Shawn D. St. Peter, Susan Adams, Shireen A. Nah, Erik D. Skarsgard, Augusto Zani, Sherif Emil, Janne S. Suominen, Dayang A. Aziz, Rambha Rai, Martin Offringa, Ernst W. van Heurn, Roel Bakx, Ramon R. Gorter

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10 Citations (Scopus)


Objective: To develop an international core outcome set (COS), a minimal collection of outcomes that should be measured and reported in all future clinical trials evaluating treatments of acute simple appendicitis in children. Summary of Background Data: A previous systematic review identified 115 outcomes in 60 trials and systematic reviews evaluating treatments for children with appendicitis, suggesting the need for a COS. Methods: The development process consisted of 4 phases: (1) an updated systematic review identifying all previously reported outcomes, (2) a 2-stage international Delphi study in which parents with their children and surgeons rated these outcomes for inclusion in the COS, (3) focus groups with young people to identify missing outcomes, and (4) international expert meetings to ratify the final COS. Results: The systematic review identified 129 outcomes which were mapped to 43 unique outcome terms for the Delphi survey. The first-round included 137 parents (8 countries) and 245 surgeons (10 countries), the second-round response rates were 61% and 85% respectively, with 10 outcomes emerging with consensus. After 2 young peoples' focus groups, 2 additional outcomes were added to the final COS (12): mortality, bowel obstruction, intraabdominal abscess, recurrent appendicitis, complicated appendicitis, return to baseline health, readmission, reoperation, unplanned appendectomy, adverse events related to treatment, major and minor complications. Conclusion: An evidence-informed COS based on international consensus, including patients and parents has been developed. This COS is recommended for all future studies evaluating treatment ofsimple appendicitis in children, to reduce heterogeneity between studies and facilitate data synthesis and evidence-based decision-making.
Original languageEnglish
Pages (from-to)1047-1055
Number of pages9
JournalAnnals of surgery
Issue number6
Early online date29 Dec 2020
Publication statusPublished - 1 Dec 2022


  • appendicitis
  • appendicitis research
  • core outcome set
  • nonoperative treatment
  • simple appendicitis

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