Perianal Abscess Recurrence and Fistula Formation: Antibiotics Following Incision and Drainage Trial

NCT04549311 | Completed Phase 3

• 1 other identifier: CTO Project ID: 2122
• Study Type: interventional
• Target: 15
• Locations: 1 country
• Sites: 3

Brief Summary

Most perianal abscesses (PA) result from an infection originating in anal crypts that extend into anal glands in the intersphincteric plane. Patients commonly present to the ER and usually require surgical intervention, which poses a burden on the healthcare system. If left undrained, a PA can expand into the adjacent tissues as well as progress to systemic infection. One of the major complications of PA are perianal fistulae; the creation of a tract between the anal canal and the perianal skin that is lined with granulation tissue or skin cells. Up to 1/3 of patients with a PA will develop a fistula; which occurs if a PA drains spontaneously through the perianal skin, and the infection becomes chronic. If this happens, surgical intervention is needed and abscesses may reoccur. Post incision and drainage (I\&D) antibiotics in PA have been used to address complications but their use is still controversial and there are no specific recommendations on their use to prevent the formations of fistulae. Recent findings from a systematic review (6 studies, N=817 patients) published in 2019 demonstrated that antibiotic use following I\&D of PA was associated with a 36% lower odds of fistula formation, though the quality of the evidence was low. As there are no established prophylactic treatments for fistulae, and because they are difficult to treat, further study of this simple intervention seems warranted. In this trial, adults with a PA requiring I\&D will be randomly assigned to receive standard of care with antibiotics or standard of care without antibiotics after I\&D. This trial will be conducted under the IMPACTS (Innovative, Multicentre, Patient-centred Approach to Clinical Trials in Surgery) program umbrella and will follow IMPACTS methodology. For the Vanguard trial, the aim is to determine the feasibility of conducting a definitive trial. Future outcomes of interest are incidence of fistula formation (defined as drainage of the perianal region at or after 2 months), need for re-intervention (i.e., any intervention on the perianal region), quality of life, healthcare utilization, healing time and mortality.

Conditions

Perianal Abscess; Perianal Fistula

Keywords

Post-operative antibiotics

Outcome Measures

Primary Outcomes (5)

• Total number of participants accrued across all sites, per month

  Feasible if 3 or more patients accrued per month between all sites

  1 year

• Proportion of participants who received the allocated intervention, across all sites

  Feasible if \>90% of patients receive correct intervention

  1 year

• Proportion of complete data collection for patient-reported outcome surveys, across all sites

  Feasible if \>80% of data is collected

  1 year

• Proportion of successful data linkage of patient-reported outcome data with Institute of Clinical Evaluative Sciences dataset(s)

  Feasible if linkage is possible in \>90% of patients

  1 year

• Estimation of fistula formation in three groups

  Rate of fistula formation in the three groups

  1 year

Study Arms (3)

Antibiotic 1 arm (amoxicillin + clavulanic acid)

ACTIVE COMPARATOR

Patients will undergo I\&D of PA by the clinician as per standard of care. This may occur in the emergency department or operating room. Patients may or may not receive packing based on the clinician's standard practice and institutional routines. Patients randomized to the antibiotic 1 arm will receive a prescription for amoxicillin + clavulanic acid (875 mg amoxicillin and 125 mg clavulanic acid BID) PO for 7 days. Otherwise, all participants will be treated identically according to the institution's standard practices.

Drug: Antibiotic 1 arm (amoxicillin + clavulanic acid)

Antibiotic 2 arm (ciprofloxacin + metronidazole)

ACTIVE COMPARATOR

Patients will undergo I\&D of PA by the clinician as per standard of care. This may occur in the emergency department or operating room. Patients may or may not receive packing based on the clinician's standard practice and institutional routines. Patients randomized to the antibiotic 2 arm will receive a prescription for ciprofloxacin + metronidazole (ciprofloxacin 500 mg and metronidazole 500 mg BID) PO for 7 days. Otherwise, all participants will be treated identically according to the institution's standard practices.

Drug: Antibiotic 2 arm (ciprofloxacin + metronidazole)

No antibiotics

NO INTERVENTION

Patients will undergo I\&D of PA by the clinician as per standard of care. This may occur in the emergency department or operating room. Patients may or may not receive packing based on the clinician's standard practice and institutional routines. In the comparator arm, patients will not receive any antibiotics. Otherwise, all participants will be treated identically according to the institution's standard practices.

Interventions

Antibiotic 1 arm (amoxicillin + clavulanic acid) DRUG

Prescription of antibiotics (amoxicillin + clavulanic acid) after incision and drainage of perianal abscess.

Antibiotic 1 arm (amoxicillin + clavulanic acid)

Antibiotic 2 arm (ciprofloxacin + metronidazole) DRUG

Prescription of antibiotics (ciprofloxacin + metronidazole) after incision and drainage of perianal abscess.

Antibiotic 2 arm (ciprofloxacin + metronidazole)

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Patients aged ≥18 years
• Perianal abscess requiring incision and drainage

You may not qualify if:

• Allergies or contraindications to amoxicillin + clavulanic acid, penicillin, ciprofloxacin, or metronidazole
• Definite need to be on antibiotics at the treating clinicians' discretion
• Immunosuppression such as: human immunodeficiency virus (HIV), chronic steroids treatment, current chemotherapy
• Abscess associated with Inflammatory Bowel Disease (IBD)
• Supralevator perianal abscess
• Recurrent perianal abscesses within 5 years
• Known rectal cancer diagnosis within 5 years
• History of pelvic radiotherapy within 5 years

Sponsors & Collaborators

• Sunnybrook Health Sciences Centre: lead

Study Sites (3)

North York General Hospital

North York, Ontario, M2K 1E1, Canada

Location

The Ottawa Hospital

Ottawa, Ontario, K1H 8L6, Canada

Location

Sunnybrook Health Sciences Centre

Toronto, Ontario, M4N 3M5, Canada

Location

MeSH Terms

Interventions

Amoxicillin; Clavulanic Acid; Ciprofloxacin; Metronidazole

Intervention Hierarchy (Ancestors)

Ampicillin; Penicillin G; Penicillins; beta-Lactams; Lactams; Amides; Organic Chemicals; Sulfur Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Heterocyclic Compounds; Clavulanic Acids; Fluoroquinolones; 4-Quinolones; Quinolones; Quinolines; Nitroimidazoles; Nitro Compounds; Imidazoles; Azoles; Heterocyclic Compounds, 1-Ring

Study Officials

• Paul Karanicolas, MD PhD

  Sunnybrook Health Sciences Centre

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Scientist and Associate Professor

Model Details: Pragmatic, multicenter, open-label, three-arm parallel-group Vanguard feasibility randomized controlled trial

Study Record Dates

• First Submitted: September 8, 2020
• First Posted: September 16, 2020
• Study Start: November 18, 2021
• Primary Completion: January 22, 2023
• Study Completion: January 22, 2023
• Last Updated: January 12, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

CA (3)