The COCOE Registry is a long-term research registry based at the Montreal Children's Hospital Colorectal Centre of Excellence (COCOE) in Montreal, Quebec. It is the first prospective registry of its kind in Canada for children with two specific colorectal conditions: Hirschsprung's disease (HD) and anorectal malformations (ARM).

What are these conditions? Hirschsprung's disease is a condition present at birth in which nerve cells are missing from part of the large intestine, making it difficult or impossible to pass stool normally. Anorectal malformations are a group of birth defects that affect the way the rectum and anus are formed. Both conditions require surgery early in life and can have lasting effects on a child's health, bowel function, quality of life, and development. Children and families affected by these conditions often face ongoing medical needs, including bowel management programs, follow-up surgeries, and psychosocial support - sometimes well into adulthood.

Why is this registry needed? Despite the significant lifelong impact of these conditions, Canada does not yet have a national database that tracks how children with HD and ARM are doing over time. Without this information, it is difficult to understand which treatments work best, how outcomes vary across different regions or populations, and what support families need most. This registry aims to fill that gap by building a rich, long-term dataset that can inform better care for current and future patients.

What is the goal of this study? The primary goals of the COCOE Registry are to: (1) establish Canada's first prospective registry for children with HD and ARM; (2) collect detailed information on diagnoses, treatments, and clinical outcomes over time; (3) understand how these conditions affect children's well-being, quality of life, and family functioning through validated patient-reported surveys; (4) identify differences in care and outcomes across regions and populations; and (5) understand why some patients are lost to follow-up and how to better support continuity of care.

Who can participate? Children between 0 and 17 years of age who have been diagnosed with Hirschsprung's disease or an anorectal malformation and are receiving care at the Montreal Children's Hospital COCOE clinic are eligible to participate. Both newly diagnosed children and those who have been followed for some time are welcome. Participation requires informed consent from the patient and/or their parent or caregiver.

What does participation involve? Participation does not involve any extra medical tests, procedures, or clinical visits beyond what is already part of the child's regular care. At each clinic visit, a member of the research team will collect information from the child's medical record, including diagnosis details, surgical history, and clinical assessments. Families will also be asked to complete short, validated surveys about the child's quality of life, bowel symptoms, general well-being, and how the family is coping. These surveys can be completed during the clinic visit, at home on paper, or online. There is no cost to participate and no financial compensation is provided, though participants will receive a certificate of participation if they wish.

How long will children be followed? Children will be followed from enrollment until they turn 18 years old. The registry itself has no planned end date and will continue enrolling new patients on an ongoing basis. It is estimated that approximately 96 new patients will join the registry each year.

How will data be protected? All data collected will be de-identified - participants will be assigned a unique registry ID, and their names will not appear on any data collection forms. Data will be stored securely in REDCap, a validated research database hosted at the Research Institute of the McGill University Health Centre (RI-MUHC). Only authorized members of the research team will have access. Participants may withdraw from the registry at any time, and their data will be destroyed upon request.

Who is conducting this study? The COCOE Registry is led by Dr. Hussein Wissanji, Pediatric Surgeon and Principal Investigator, with co-investigator Dr. Etienne St-Louis, both from the Harvey E. Beardmore Division of Pediatric Surgery at Montreal Children's Hospital. The study has been approved by the McGill University Health Centre Research Ethics Board (REB No. 2026-10997). Funding is provided through internal research funds.

How will findings be shared? Results from the registry will be shared through scientific publications, conference presentations, and patient-friendly materials such as blog posts and infographics, developed with input from patient and family partners. Individual participant results will not be shared, but families can request access to their own registry file to verify the accuracy of their data.

BACKGROUND AND RATIONALE Colorectal disorders - particularly Hirschsprung's disease (HD) and anorectal malformations (ARM) - represent some of the most complex and consequential conditions in pediatric surgery. Both are present from birth, require early surgical intervention, and carry lifelong implications for affected children and their families. In Canada, these conditions affect thousands of children, yet the country lacks a national prospective registry to systematically track their diagnosis, treatment, and long-term outcomes.

The Montreal Children's Hospital Colorectal Centre of Excellence (COCOE) was established as the first multidisciplinary colorectal center of its kind in Quebec. The COCOE brings together pediatric surgeons, gastroenterologists, urologists, nurses, psychologists, dietitians, and other specialists to provide comprehensive, coordinated care for children with HD, ARM, and related colorectal conditions. This integrated model of care represents best practice in the management of complex pediatric colorectal disease. However, the absence of a systematic, prospective data registry has limited the center's ability to evaluate outcomes rigorously, benchmark against international peers, and contribute meaningfully to the global evidence base.

STUDY DESIGN AND METHODOLOGY The COCOE Registry is a longitudinal, prospective observational study. Patients are recruited from the outpatient pediatric colorectal clinic at Montreal Children's Hospital and followed from enrollment until they reach 18 years of age. Both newly diagnosed patients and those who have been previously diagnosed and are returning for ongoing care are eligible for enrollment. The registry has no planned end date and will enroll patients on a continuous basis. An anticipated enrollment rate of at least five new patients per month - plus re-engagement of approximately three patients per month who had previously been lost to follow-up - yields an estimated 96 newly enrolled participants per year.

The registry follows a strictly observational design: no experimental interventions are performed, and research participation has no bearing on the clinical care that patients receive. Data collection is embedded within the existing clinical workflow of COCOE visits, minimizing additional burden on participants and clinical staff. All data collected are either drawn from existing medical records or obtained through validated questionnaires that are administered as part of standard clinical practice.

STUDY POPULATION Eligible participants are children between 0 and 17 years of age with a documented diagnosis of Hirschsprung's disease or an anorectal malformation who are receiving care at the COCOE clinic. Patients must be able to provide informed consent, either directly (for older children with capacity) or through a parent, caregiver, or authorized representative. Patients over 18 years of age, those without a confirmed diagnosis of HD or ARM, and those unable to provide consent are excluded from participation. When a participant turns 18, data collection stops and the participant is invited to re-consent as an adult if continued follow-up is desired.

ETHICAL FRAMEWORK The COCOE Registry is conducted in full accordance with the Tri-Council Policy Statement: Ethical Conduct for Research Involving Humans (TCPS2, 2022) and the applicable standard operating procedures of the Research Institute of the McGill University Health Centre. The study has been reviewed and approved by the McGill University Health Centre Research Ethics Board (MUHC REB No. 2026-10997). The MUHC REB is responsible for ongoing monitoring and annual review of the registry protocol.

SIGNIFICANCE AND ANTICIPATED IMPACT The COCOE Registry represents a significant and long-overdue contribution to the Canadian pediatric colorectal landscape. By systematically capturing clinical data and patient-reported outcomes for children with HD and ARM over the course of their childhood and adolescence, the registry will generate the evidence base needed to answer fundamental questions about long-term outcomes, treatment effectiveness, disparities in care, and the lived experience of patients and families in Canada.

Inclusion Criteria

• Age 0 to 17 years at time of enrollment
• Documented diagnosis of Hirschsprung's disease or an anorectal malformation
• Receiving care at the Montreal Children's Hospital Colorectal Centre of Excellence (COCOE)
• Patient and/or parent, caregiver, or authorized representative is able to provide informed consent or assent in accordance with applicable institutional and ethical requirements

Exclusion Criteria

• Age 18 years or older at time of enrollment
• No confirmed diagnosis of Hirschsprung's disease or anorectal malformation
• Unable to provide informed consent or assent

The study population consists of pediatric patients aged 0 to 17 years with a confirmed diagnosis of Hirschsprung's disease (HD) or an anorectal malformation (ARM) who are receiving care at the Colorectal Centre of Excellence (COCOE) at Montreal Children's Hospital, McGill University Health Centre, in Montreal, Quebec, Canada. Both newly diagnosed patients and those with previously established diagnoses who are returning for ongoing follow-up care are eligible for enrollment.

The registry enrolls patients across the full pediatric age spectrum, from the newborn period through late adolescence, allowing for longitudinal tracking of outcomes across critical developmental stages including infancy, early childhood, school age, and the transition to adulthood. Patients are followed until they reach 18 years of age, at which point data collection stops and participants are invited to re-consent as adults if continued follow-up is desired.

There is no plan to share individual participant data (IPD) with external researchers at this time. All data collected through the COCOE Registry are de-identified at the point of entry and stored under unique registry identifiers within a secure REDCap database hosted at the Research Institute of the McGill University Health Centre (RI-MUHC). Access to registry data is restricted to authorized members of the research team.