Restricted or Liberal Antibiotics After Appendectomy - Denver Health (CASA RELAX)

October 30, 2025 updated by: Daniel Yeh, Denver Health and Hospital Authority

Complex And Simple Appendicitis: REstrictive or Liberal Post-operative Antibiotic eXposure (CASA RELAX) Using Desirability of Outcome Ranking (DOOR) and Response Adjusted for Duration of Antibiotic Risk (RADAR): A Randomized Controlled Trial at Denver Health

The purpose of this study is to see if decreasing the amount of antibiotics after appendicitis surgery can decrease the risk of adverse effects associated with antibiotics while at the same time ensuring participant safety.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

657

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Colorado
      • Denver, Colorado, United States, 80204-4507
        • Denver Health and Hospital Authority

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age ≥ 18 years
  • Planned appendectomy (laparoscopic or open) for simple or complicated (perforated or gangrenous) appendicitis
  • Working telephone number or reliable method to contact patient after hospital discharge

Exclusion Criteria:

  • Unable to consent
  • Pregnant Women
  • Prisoners
  • Immunocompromised as determined by clinical team, or patients actively receiving steroids, chemotherapy, or immunosuppressing medications (for example tacrolimus), or patients with active hematologic malignancy affecting the immune system, leukopenia, or end-stage AIDS
  • Heart failure
  • Allergy to bupivacaine
  • Unlikely to comply with treatment or follow-up
  • Inpatient consultation for appendicitis
  • Clinically suspected of sepsis based on Sepsis-3 definition
  • Current use of antibiotics for other indications
  • Uncontrolled hyperglycemia or Type 1 Diabetes
  • Surgeon preference
  • Patient preference
  • Research team unavailable

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Restricted Post-Operative Antibiotics Group

Participants undergoing standard of care (SOC) with simple appendicitis will not receive post-operative antibiotics.

Participants undergoing standard of care with complicated (gangrenous or perforated) appendicitis will receive up to 24 hours of SOC post-operative antibiotics.
Other: Restricted Duration of SOC Antibiotic Use
Standard of Care Antibiotic use will be restricted to none or up to 24 hours of post-operative antibiotics.
Active Comparator: Liberal Post-Operative Antibiotics Group

Participants undergoing standard of care with simple appendicitis will receive 24 hours of post-operative SOC antibiotics

Participants undergoing standard of care with complicated (gangrenous or perforated) appendicitis will receive 4 days of post-operative SOC antibiotics.
Other: Liberal Duration of SOC Antibiotic Use
Standard of Care Antibiotic use will be permitted for 24 hours or up to 4 days of post-operative antibiotics.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of participants with no antibiotic related adverse effects
Time Frame: Up to 40 days after appendicitis surgery
As assessed by treating physician
Up to 40 days after appendicitis surgery
Incidence of Infectious/Antibiotic Complications
Time Frame: Up to 30 days after appendicitis surgery
Infectious/antibiotic complication requiring antibiotic treatment only, Emergency Department visit, hospital readmission, percutaneous drainage, and operative intervention as assessed by treating physician.
Up to 30 days after appendicitis surgery
Number of participant deaths
Time Frame: Up to 30 days after appendicitis surgery
As assessed by treating physician
Up to 30 days after appendicitis surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Denver Health and Hospital Authority

Investigators

  • Principal Investigator: Daniel D Yeh, MD, MHPE, Denver Health and Hospital Authority

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

November 1, 2021

Primary Completion (Actual)

July 16, 2025

Study Completion (Actual)

July 16, 2025

Study Registration Dates

First Submitted

August 4, 2021

First Submitted That Met QC Criteria

August 4, 2021

First Posted (Actual)

August 12, 2021

Study Record Updates

Last Update Posted (Estimated)

October 31, 2025

Last Update Submitted That Met QC Criteria

October 30, 2025

Last Verified

October 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 20191238

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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