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Dear ACPGBI members,

We would like to invite all ACPGBI members that are interested in the treatment of cryptoglandular anal fistula to participate in an international Delphi consensus process to develop a Core Outcome Measurement Set for Cryptoglandular anal fistula.

There is substantial heterogeneity within clinical research evaluating cryptoglandular anal fistula, in the outcomes used and their associated measurement instruments.  This heterogeneity hinders the comparison and synthesis of results across studies and slows research advances in the field.  To help address this issue, the 'Anal Fistula Core Outcome Set' for clinical research has been developed.  This Core Outcome Set is a minimum set of outcomes that should be used in all research relevant to a specific field.

The next step will be to determine the definitions and appropriate measurement instruments for each core outcome.  This will be undertaken using a modified Delphi Consensus process based on research and guidance for developing Core Outcome Sets.  The panel will consist of representatives from a wide variety of stakeholder groups, including clinician/professional associations, national / regional clinical research groups and investigators, and patients who have been treated for cryptoglandular fistula.

We would like to invite you to be part of the Delphi panel.  The Delphi process will involve completion of at least 2 rounds of web-based surveys using the Qualtrics platform.  This iterative consensus process will involve completing a survey with your recommendations, followed by subsequent feedback on your responses in comparison to the group's responses.  This will be followed by repeated completion of the survey.  The process will be repeated to determine measurement instruments for each core outcome.  To reach a final consensus, an online consensus meeting will be held, after completion of the two rounds.  This will last approximately 1.5 hours.  

This process will be conducted electronically. It is very important that each participant be willing to carefully complete each round of the web-based Delphi survey on a timely basis. The reliability of Delphi consensus results will be compromised if panel members drop-out.

The questionnaire can be accessed using the following link:

The deadline for the first round of the Delphi consensus process is set on 17 September 2023.

If you require further information, please do not hesitate to contact us at

We look forward to your responses!

Kind regards,

- Stéphanie Breukink, Associate Professor Colorectal Surgery at the Maastricht University Medical Centre,

- Phil Tozer, Colorectal Surgeon, St Mark's Hospital and Academic Institute 

- Litza Mitalas, Surgeon at the Maastricht University Medical Centre and,

- Merel Kimman, Researcher at Maastricht University Medical Centre.

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