Perianal AbscessPhase 3PARFAITNCT04549311
Perianal Abscess Recurrence and Fistula Formation: Antibiotics Following Incision and Drainage Trial
A Phase 3 study testing Antibiotic 1 arm (amoxicillin + clavulanic acid) and Antibiotic 2 arm (ciprofloxacin + metronidazole) in people with Perianal Abscess and Perianal Fistula, run by Sunnybrook Health Sciences Centre at 3 sites in Canada.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Perianal Abscess, Perianal Fistula
- What is being tested?
- Antibiotic 1 arm (amoxicillin + clavulanic acid) and Antibiotic 2 arm (ciprofloxacin + metronidazole)
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 15 participants
- Where
- 3 sitesCanada
- Study dates
- 18 Nov 2021to 22 Jan 2023
- Phase
- Phase 3
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Patients aged ≥18 years
- Perianal abscess requiring incision and drainage
Who cannot join
- 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
Trial locations and contacts
3 sites in 1 country.
Canada3 sites
North York General Hospital
North York, Ontario, M2K 1E1
The Ottawa Hospital
Ottawa, Ontario, K1H 8L6
Sunnybrook Health Sciences Centre
Toronto, Ontario, M4N 3M5
About this study
Official title: Perianal Abscess Recurrence and Fistula Formation: Antibiotics Following Incision and Drainage Trial - (PARFAIT) A Vanguard Randomized Controlled Trial
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.
Read the detailed description
The development of perianal abscesses is relatively common with an estimated incidence in the UK of 40 per 100,000 habitants (Canadian incidence unknown). It is uncertain if there is any benefit to using prophylactic antibiotics after incision and drainage of a perianal abscess in order to reduce the formation of fistulae, the need for re-intervention, health system costs, and healing time. Further research from high-quality RCTs is needed to establish a benefit, if any, for this practice.
Objectives: Before embarking on a definitive RCT, this pilot trial has five specific feasibility objectives:
- To assess our ability to accrue patients using the IMPACTS Program design platform at multiple institutions, over the course of one year.
- To assess our ability to adaptively randomize patients and deliver the randomized assignment using the IMPACTS Program design platform, over the course of one year.
- To assess our ability to collect complete data directly from participants (patients and clinicians) on: re-intervention, fistula formation, quality of life, and healing time over the course of one year.
- To examine our ability to carry out data linkages using the IMPACTS Program design platform over the course of one year.
- To estimate the incidence of fistula formation to inform the sample size calculation for the definitive trial.
Study design: This is a multicentre, pragmatic, open label, three-arm parallel-group Vanguard feasibility randomized controlled trial. Adult patients with perianal abscesses requiring incision and drainage will be randomized to receive standard of care with antibiotics or standard of care without antibiotics after incision and drainage. If feasibility is demonstrated during the pilot trial, we will plan to conduct a definitive trial. If there are only minimal changes to the protocol, we will include data from the pilot phase into the definitive trial analysis (i.e. a Vanguard design).
- Conditions
- Perianal Abscess, Perianal Fistula
- Being tested
- Antibiotic 1 arm (amoxicillin + clavulanic acid), Antibiotic 2 arm (ciprofloxacin + metronidazole)
- Keywords
- Post-operative antibiotics
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Antibiotic 1 arm (amoxicillin + clavulanic acid)Drug
Prescription of antibiotics (amoxicillin + clavulanic acid) after incision and drainage of perianal abscess.
Antibiotic 2 arm (ciprofloxacin + metronidazole)Drug
Prescription of antibiotics (ciprofloxacin + metronidazole) after incision and drainage of perianal abscess.
| Study group | Role | What they receive |
|---|---|---|
| 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. Receives: 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. Receives: 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. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Total number of participants accrued across all sites, per month
Feasible if 3 or more patients accrued per month between all sites
Measured: 1 year
Proportion of participants who received the allocated intervention, across all sites
Feasible if >90% of patients receive correct intervention
Measured: 1 year
Proportion of complete data collection for patient-reported outcome surveys, across all sites
Feasible if >80% of data is collected
Measured: 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
Measured: 1 year
Estimation of fistula formation in three groups
Rate of fistula formation in the three groups
Measured: 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 Sep 2020
- Study start18 Nov 2021
- Primary completion22 Jan 2023
- Study completion22 Jan 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Perianal AbscessStudies of the same condition, open and under way.
- More trials run by Sunnybrook Health Sciences CentreThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Pragmatic, multicenter, open-label, three-arm parallel-group Vanguard feasibility randomized controlled trial
- Masking
- None (open label)
- Enrolment
- 15 participants (actual)
Sponsor and investigators
- Lead sponsor
- Sunnybrook Health Sciences Centre
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Dr. Paul Karanicolas, Sunnybrook Health Sciences Centre
- Investigators
- Paul Karanicolas, MD PhD, Principal investigator, Sunnybrook Health Sciences Centre
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04549311
- Sponsor's protocol ID
- CTO Project ID: 2122
- Acronym
- PARFAIT
- Status last verified
- Jan 2026
- First submitted
- 8 Sep 2020
- Last updated
- 12 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 12 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Perianal Abscess Recurrence and Fistula Formation: Antibiotics Following Incision and Drainage Trial - (PARFAIT) A Vanguard Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT04549311
- Acronym / sponsor ID
- PARFAIT / CTO Project ID: 2122
- Conditions
- Perianal Abscess, Perianal Fistula
- Keywords
- Post-operative antibiotics
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 15 participants (actual)
- Lead sponsor
- Sunnybrook Health Sciences CentreUniversity, hospital or other
- Study start
- 18 Nov 2021 (actual)
- Primary completion
- 22 Jan 2023 (actual)
- Study completion
- 22 Jan 2023 (actual)
- First posted
- 16 Sep 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
The development of perianal abscesses is relatively common with an estimated incidence in the UK of 40 per 100,000 habitants (Canadian incidence unknown). It is uncertain if there is any benefit to using prophylactic antibiotics after incision and drainage of a perianal abscess in order to reduce the formation of fistulae, the need for re-intervention, health system costs, and healing time. Further research from high-quality RCTs is needed to establish a benefit, if any, for this practice.
Objectives: Before embarking on a definitive RCT, this pilot trial has five specific feasibility objectives:
- To assess our ability to accrue patients using the IMPACTS Program design platform at multiple institutions, over the course of one year.
- To assess our ability to adaptively randomize patients and deliver the randomized assignment using the IMPACTS Program design platform, over the course of one year.
- To assess our ability to collect complete data directly from participants (patients and clinicians) on: re-intervention, fistula formation, quality of life, and healing time over the course of one year.
- To examine our ability to carry out data linkages using the IMPACTS Program design platform over the course of one year.
- To estimate the incidence of fistula formation to inform the sample size calculation for the definitive trial.
Study design: This is a multicentre, pragmatic, open label, three-arm parallel-group Vanguard feasibility randomized controlled trial. Adult patients with perianal abscesses requiring incision and drainage will be randomized to receive standard of care with antibiotics or standard of care without antibiotics after incision and drainage. If feasibility is demonstrated during the pilot trial, we will plan to conduct a definitive trial. If there are only minimal changes to the protocol, we will include data from the pilot phase into the definitive trial analysis (i.e. a Vanguard design).
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
- Model description
- Pragmatic, multicenter, open-label, three-arm parallel-group Vanguard feasibility randomized controlled trial
| Arm | Type | Receives |
|---|---|---|
| Antibiotic 1 arm (amoxicillin + clavulanic acid) | Active comparator | Drug: Antibiotic 1 arm (amoxicillin + clavulanic acid)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. |
| Antibiotic 2 arm (ciprofloxacin + metronidazole) | Active comparator | Drug: Antibiotic 2 arm (ciprofloxacin + metronidazole)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. |
| 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. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- Patients aged ≥18 years
- Perianal abscess requiring incision and drainage
Key exclusion criteria (8 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Antibiotic 1 arm (amoxicillin + clavulanic acid)Prescription of antibiotics (amoxicillin + clavulanic acid) after incision and drainage of perianal abscess. | Drug | Antibiotic 1 arm (amoxicillin + clavulanic acid) |
| Antibiotic 2 arm (ciprofloxacin + metronidazole)Prescription of antibiotics (ciprofloxacin + metronidazole) after incision and drainage of perianal abscess. | Drug | Antibiotic 2 arm (ciprofloxacin + metronidazole) |
Primary outcome
Total number of participants accrued across all sites, per month
Time frame: 1 year
Feasible if 3 or more patients accrued per month between all sites
Proportion of participants who received the allocated intervention, across all sites
Time frame: 1 year
Feasible if >90% of patients receive correct intervention
Proportion of complete data collection for patient-reported outcome surveys, across all sites
Time frame: 1 year
Feasible if >80% of data is collected
Proportion of successful data linkage of patient-reported outcome data with Institute of Clinical Evaluative Sciences dataset(s)
Time frame: 1 year
Feasible if linkage is possible in >90% of patients
Estimation of fistula formation in three groups
Time frame: 1 year
Rate of fistula formation in the three groups
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 Jan 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Paul Karanicolas, MD PhD principal investigator
Sunnybrook Health Sciences Centre
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Antibiotic 1 arm (amoxicillin + clavulanic acid) and Antibiotic 2 arm (ciprofloxacin + metronidazole) in people with Perianal Abscess and Perianal Fistula, run by Sunnybrook Health Sciences Centre at 3 sites in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 12 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Total number of participants accrued across all sites, per month (time frame: 1 year). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 12 Jan 2026.