Core Outcome Measures in Effectiveness Trials

The development of a core outcome set for pouch anal fistula - An international Delphi study

General Information

The ileal pouch anal anastomosis (IPAA) was first described in 1978 by Sir Alan Parks and Professor John Nicholls at St Mark's hospital. The IPAA was developed with the aim of avoiding a permanent ileostomy following a total proctocolectomy for ulcerative colitis or familial adenomatous polyposis syndrome. This restorative procedure involves the use of terminal ileum to create a reservoir for effluent, thereby preserving gastrointestinal continuity. The IPAA is a safe procedure with evidence demonstrating improved quality of life and patient satisfaction, when compared to the alternative, a permanent ileostomy. Nevertheless, there are significant complications of the ileoanal pouch, such as the development of a pouch anal or pouch vaginal fistula. These fistulae can be very challenging to manage, and often lead to pouch failure, amounting eventually to a defunctioning ileostomy with or without a pouch excision. There are various treatment options available for pouch anal fistulae. These are related to the clinical and anatomical presentation of the fistulae. There are no objective measures available for establishing the success of these treatments. Often different treatment strategies may need to be adopted depending on the classification of the pouch anal fistula. Meaningful comparison of treatment strategies is not possible in the absence of standardised primary and secondary outcomes for pouch anal fistula. Future research and development in the management of these fistulae will rely on the establishment of a core outcome set for pouch anal fistula. We intend to develop a core outcome set for pouch anal fistula using Delphi principles to aid research and improve clinical practice.

Principal Investigator :
Mr Phil Tozer, Consultant Colorectal surgeon, St Mark's Academic institute/Imperial college London

Professor Sue Clark, Consultant Colorectal surgeon, St Mark's Academic unit/Imperial College London
Professor Ailsa Hart, Consultant Gastroenterologist, St Mark's Academic unit/ Imperial College London

Clinical Research fellow:
Ms Lillian Mariam Reza

Further Study Information

Current Stage:
March 2020 - March 2021
Funding source(s):
To be confirmed

Health Area

Disease Category

Disease Name
Pouch anal fistula

Target Population

Age Range
18 - 120


Nature / type of Intervention


Consensus meeting
Delphi process
Systematic review

Mixed methodology will be used to develop a core outcome set. We intend to involve the four main stakeholders for pouch anal fistula: 1. Patients 2. Colorectal Surgeons 3. Gastroenterologists 4. Radiologists. A COS will be developed in a step wise fashion as per the COMET initiative.
1. Systematic review
A systematic review of interventions and management of pouch anal fistula will be carried out according to the PRISMA statement. This will be used to generate a list of reported outcomes, outcomes measurement tools and timing of the measurement of outcomes. Two members of the study team will extract the data and group the outcomes. Consensus will be reached through discussion with the aid of senior investigators in case of disagreements.
2. Semi-structured qualitative patients interviews
We intend to include a diverse and representative patient population. Patient recruitment will therefore involve social media, national and international patient groups, national charities as well as recruitment from the outpatient colorectal clinics at St Mark's Hospital. Semi structured interviews will be used to identify outcomes that are relevant to patients but have not been captured in our systematic review.
3. The clinician and patient reported outcomes will be categorised into domains using OMERACT filter 2.0 by the study team. The study team will deliberate and discuss the mapping of the outcomes in to core areas and domains but will not guide the COS formation. The outcomes will be formatted in to questions to develop a questionnaire for use in the Delphi consensus process. The questionnaire will undergo review and development using patient and clinician pilot groups prior to use in the Delphi process
4. Three rounds of the Delphi process will be used to facilitate convergence to a consensus opinion on the core outcomes. An anonymised web based questionnaire will be used to enable international participation from all stakeholder groups. Clinician participation (surgeons, radiologists and gastroenterologists) will be recruited through national and international speciality organisations. Prioritisation of candidate outcomes on the questionnaire will be based on a 9 –point Likert scale. Participants will be given the opportunity to suggest outcomes that they feel are relevant but are absent from the questionnaire. These will be incorporated as appropriate in to the questionnaire of the second Delphi round. Participants will receive anonymised feedback on the prioritisation of the outcomes from the collective group compared to their individual responses. This will enable participants to review prioritisation of outcomes and allow convergence to consensus. A third Delphi round will repeat the above process and recruit participants for the face-to-face consensus meeting.
5. Consensus meeting
Patients and health care professionals who have participated in all the Delphi rounds will be invited to a face-to-face meeting to finalise the core outcome set. An equal number of participants for each stakeholder group will be selected for the meeting. Each outcome will be reviewed and will either be kept or removed depending on whether they receive a Likert rating 7-9 by >70% of the group. Anonymous, electronic voting will be used. A core outcome set for pouch fistula will be generated at the end of the process.

Stakeholders Involved

Clinical experts
Patient/ support group representatives
Policy makers
Service providers
Service users

Study Type

COS for clinical trials or clinical research
COS for practice

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