A Patient Classification System for Perianal Fistulizing in Crohn Disease

Researchers developed a classification system for identifying patients with perianal fistulizing Crohn disease and recommended treatment strategies.

An expert panel published a consensus statement aimed at helping guide the classification of perianal fistulizing in Crohn disease (CD). The statement was published in The Lancet Gastroenterology and Hepatology.

The immune-mediated chronic condition CD occurs among approximately 300 per 100,000 individuals in Western countries. CD can present as various phenotypes and 14% to 43% of patients have perianal fistulizing CD, which is an aggressive form associated with chronic, disabling symptoms. Patients with perianal fistulizing CD often have disability and psychological, sexual, and social problems with frequent hospital admissions.

Current treatment strategies for this subset of patients include antibiotics, immunomodulators, biologic drugs, and surgical repair. However, these approaches have limited efficacy and patients have increased risk for requiring temporary or permanent defunctioning stoma and/or proctectomy.

Likely related with the lack of effective treatments, previous patient classification systems neither provide clear guidance on which patients should receive which therapies nor do they define patient cohorts for clinical trials.

The expert panel proposed a new patient classification system that considers disease severity and outcomes using a combined medical and surgical approach. In addition, the classification system has components about the patient’s personal treatment goals and symptom burden.

The classification system comprises 4 principal groups:

  • Class 1: patients with minimal disease
  • Class 2: patients with chronic symptoms requiring repair attempt (Class 2a), symptom control (Class 2b), or that lead to a defunctioning ostomy (Class 2c)
  • Class 3: patients who require proctectomy
  • Class 4: patients who have persistent symptoms after proctectomy requiring repair attempt (Class 4a) or symptom control (Class 4b)

This classification system was designed to be flexible, in which a patient with chronic symptomatic fistulae may cycle through differing classes as their disease progresses or when their personal treatment goals change.

Class 1 consists of patients with the least severity. In general, there has been little attention paid to these patients, and they are rarely seen in a tertiary care setting. Classifying patients as Class 1 is largely driven by the patient. If the patient does not perceive their symptoms as burdensome, they likely would not want to undergo intervention. The panel states that additional investigation and validation of minimal perianal fistulizing CD symptomology is needed.

Class 2 is made up of 3 subgroups of patients with chronic symptomatic perianal fistulae and stratifying patients into 1 of the 3 subgroups relies on surgical eligibility and the patient’s treatment goals. Patients who are suitable for combined medical and surgical closure are grouped into Class 2a, and those who are not candidates for surgical closure but want to gain symptom control are in Class 2b. Class 2c is further subdivided into 2 groups based on disease progression. Patients who have early and rapidly progressive disease that is destructive to the perineum are in Class 2c-i, and those with gradually debilitating disease who are unsuitable for surgical repair are in Class 2c-ii.

Treatment for Class 2 includes optimally timed surgical intervention with medical treatment (2a), best medical treatment (2b), rapid, combined medical and surgical treatment to drain and control disease (2c-i), and medical treatment and consideration of defunctioning ostomy (2c-ii). These patients could be suitable for clinical trials of interventions that best align with their subgroup.

Class 3 consists of patients who have severely symptomatic disease despite defunctioning, have irreversible perineal destruction, and/or limited quality of life. Clinicians should discuss proctectomy with these patients. At trial, these patients would most likely be candidates for interventions aimed at improving quality of life and/or avoiding sinus or wounds.

Class 4 includes the most severe patients who experience persistent perineal symptoms after undergoing proctectomy. Patients who are eligible to undergo surgical closure or repair are grouped into Class 4a and those who are not candidates for surgery and are managed with best medical treatment are in Class 4b. These patients could be eligible for clinical trials aimed at evaluating sinus or wound closure and/or quality of life.

The panel authors concluded, “This classification system is the first of its kind and is an important step towards tailored standardization of clinical practice and research in patients with perianal fistulizing CD. Future efforts will focus on more precise definition of some of the abstract terminology in the proposed system and, eventually, the goal is to validate this system both retrospectively and prospectively.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please refer to the original reference for a full list of authors’ disclosures.


Geldof J, Iqbal N, LeBlanc J-F, et al. Classifying perianal fistulising Crohn’s disease: an expert consensus to guide decision-making in daily practice and clinical trials. Lancet Gastroenterol Hepatol. Published online March 21, 2022. doi:10.1016/S2468-1253(22)00007-3