Perforated Appendicitis and Postoperative Antibiotics Pilot Trial (PAPA Pilot)

The goal of this clinical trial is to learn if not giving antibiotics is as effective as giving antibiotics after surgery for patients who have surgery for a perforated (burst) appendix. This pilot study will also help determine whether a larger, multi-centre study can be successfully conducted. The main questions it aims to answer are:

• Do patients who do not receive antibiotics after surgery have similar rates of infection after surgery as patients who do?
• Is it feasible to enroll and randomize patients and collect complete health data for a larger multi-centre study?

Researchers will compare patients who do not receive antibiotics after surgery to patients who do to see whether avoiding antibiotics is as effective as using antibiotics for preventing infections after surgery.

Participants will:

• Be randomly assigned to either receive or not receive antibiotics after surgery for their perforated (burst) appendix.
• Be contacted 30 and 90 days after surgery to check for infections and other health outcomes.

Study Overview

• Status: Not yet recruiting
• Conditions: Perforated Appendicitis
• Intervention / Treatment: Drug: Postoperative antibiotico-prophylaxis; Other: No postoperative antibiotics

Detailed Description

Acute appendicitis, a sudden and severe inflammation of the appendix, is the most common emergency general surgery condition worldwide. In some cases, the appendix perforates, leading to contamination or infection within the abdominal cavity. Complicated appendicitis is associated with higher morbidity and mortality, including a higher risk of surgical site infections (SSIs). Approximately 20% of patients with complicated appendicitis develop an SSI, compared to about 5% of patients with uncomplicated appendicitis.

The use of antibiotics before surgery is well established and standard practice to reduce SSI risk. However, there is limited evidence to guide the use of antibiotics after surgery in patients with complicated appendicitis. Antibiotics carry potential risks, including allergic reactions, gastrointestinal side effects, and secondary infections, and their overuse contributes to antimicrobial resistance, which is a growing global health concern. As a result, there is a considerable variation in clinical practice, with some surgeons routinely prescribing post-operative antibiotics and others choosing not to.

Large, high-quality randomized controlled trials (RCTs), the gold-standard in clinical research, are needed to understand if post-operative antibiotics are necessary in this population. The current study will evaluate the impact of post-operative antibiotics on SSIs in patients with perforated appendicitis. This pilot specifically aims to determine the feasibility of a larger, multi-centre RCT, and will assess our ability to enroll and randomize patients, and to collect complete health data using an existing framework. Patients will be randomly assigned to receive post-operative antibiotics or no post-operative antibiotics after surgery for perforated appendicitis, and will be followed until 30 days after surgery to assess incidence of SSIs, with additional outcomes collected up to 90 days post-surgery.

• Study Type: Interventional
• Enrollment (Estimated): 100
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults aged 18 years or older
• Scheduled to undergo an open or laparoscopic appendectomy
• Complicated appendicitis confirmed intra-operatively (AAST Appendicitis Grade III or IV)

Exclusion Criteria:

• Patients demonstrating signs of septic shock for whom the omission of systemic antibiotics is contraindicated
• Patients with positive blood cultures for whom antibiotics are required for treatment of the bacteremia
• Immunosuppressed patients
• AAST Appendicitis Grade V

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Postoperative antibiotics; Patients receive antibiotics following surgery for perforated appendicitis.	Drug: Postoperative antibiotico-prophylaxis; Patients receive oral antibiotics following surgery for perforated appendicitis. The dose, duration, and type are at the discretion of the treating physician.
Active Comparator: No postoperative antibiotics; Patients do not receive antibiotics following surgery for perforated appendicitis.	Other: No postoperative antibiotics; Patients do not receive antibiotics following surgery for perforated appendicitis.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Average number of participants enrolled per month across multiple sites.	Assessment of accrual: feasible if 10 or more overall.	First to last day of each month of recruitment phase (1 year).
Percentage of participants who receive the correct intervention.	Assessment of ability to accurately deliver the intervention that participants were randomized to receive: feasible if >90% of participants receive the assigned intervention.	From beginning to end of recruitment phase (1 year).
Percentage of patient-reported outcomes collected.	Assessment of ability to collect complete data for patient reported outcomes. Feasible if >80% of data is collected directly from patients with an additional 10% collected from patient health records.	Duration of the study (1 year). For each participant, data collected 30 and 90 days after surgery.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Quality of Life, as assessed by EQ-5D-5L.	Level Sum Score can be calculated, ranging from 5 to 25, with higher scores representing a worse health status.	30 and 90 days after surgery for perforated appendicitis.
Post-operative pain, as assessed by PROMIS Pain Inventory.	5-point Likert scale, with higher scores (i.e., 5 or "very much") indicating higher levels of pain.	30 days after surgery for perforated appendicitis.
Percentage of patients with surgical site infections, as assessed by Participant Assessment of Surgical Wound questionnaire.	5 questions (4 yes/no answers, 1 check all that apply).	30 days after surgery for perforated appendicitis.
Percentage of participants prescribed systemic antibiotics.	Collected from Participant Assessment of Surgical Wound questionnaire or patient health records.	Within 30 days after surgery for perforated appendicitis.
Post-operative complications, as assessed by Health Resource Utilization questionnaire.	6 questions (5 yes/no, 1 check all that apply).	Within 90 days after surgery for perforated appendicitis.
Healthcare utilization, as assessed by Health Resource Utilization questionnaire.	Healthcare utilization, including number of: reinterventions, all-cause reoperations, emergency department visits, all-cause unplanned family physician or walk-in clinic visits, and all-cause readmissions and length of stay of each readmission.	Within 90 days after surgery for perforated appendicitis.

Collaborators and Investigators

• Sponsor: London Health Sciences Centre Research Institute OR Lawson Research Institute of St. Joseph's
• Collaborators: Sunnybrook Health Sciences Centre

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): September 1, 2027
• Study Completion (Estimated): November 1, 2027

Study Registration Dates

• First Submitted: June 1, 2026
• First Submitted That Met QC Criteria: June 15, 2026
• First Posted (Actual): June 18, 2026

Study Record Updates

• Last Update Posted (Actual): June 18, 2026
• Last Update Submitted That Met QC Criteria: June 15, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Randomized controlled trial; Pilot trial; Complicated appendicitis; Emergency general surgery; Perforated appendicitis; Postoperative antibiotics; Acute care surgery
• Additional Relevant MeSH Terms: Intestinal Diseases; Infections; Digestive System Diseases; Gastrointestinal Diseases; Gastroenteritis; Cecal Diseases; Intraabdominal Infections; Appendicitis
• Other Study ID Numbers: 5867

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No