AFCOS: The Development of a Cryptoglandular Anal Fistula Core Outcome Set

Nusrat Iqbal*, Astrid J H M Machielsen, Merel L Kimman, Gillian Kane, Rebecca Woodcock, Ugo Grossi, Phil J Tozer, Stéphanie O Breukink, AFCOS Consensus Meeting Collaborators

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


OBJECTIVE: To develop a cryptoglandular Anal Fistula Core Outcome Set: a minimum set of outcomes that should be measured in all studies of cryptoglandular anal fistula treatment.

BACKGROUND: Variability in the outcomes that are reported in studies of cryptoglandular anal fistula treatment hampers systematic evidence synthesis to identify the best treatment.

METHODS: This study followed guidance from the Core Outcome Measures in Effectiveness Trials initiative and consisted of three stages: (1) generation of candidate outcomes through systematic review of the literature and qualitative patient interviews; (2) prioritization of outcomes by key stakeholders, including patients, surgeons, gastroenterologists, and radiologists in an online Delphi consensus process; and (3) determination of the final Core Outcome Set (COS) in a consensus meeting attended by patients and clinicians.

RESULTS: Sixty-four outcomes were presented in the first Delphi survey round. A total of 191 participants from over 30 countries ranked these outcomes according to their importance in defining treatment success (57.6% surgeons and gastroenterologists, 8.9% radiologists, and 33.5% patients). After two rounds, 53 outcomes were identified as important and discussed in the consensus meeting attended by 10 patients and 12 clinicians. A final 10 outcomes were voted into the COS: clinical fistula healing, radiological healing, recurrence, development of additional fistulas, fistula symptoms, incontinence, psychological impact of treatment, complications and reinterventions, patient satisfaction, and quality of life.

CONCLUSION: The final COS represents an international, multidisciplinary, patient-centered attempt to establish consistency in fistula research, with a substantial focus on patient priorities for treatment.

Original languageEnglish
Pages (from-to)E1045-E1050
Number of pages6
JournalAnnals of Surgery
Issue number5
Early online date11 Jul 2022
Publication statusPublished - May 2023


  • Core Outcome Set
  • Delphi consensus
  • Anal fistula
  • Outcomes


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