Project Summary

PCORI has identified the need for large studies that look at real-life questions faced by diverse patients, caregivers, and clinicians. To address this need, PCORI launched the Pragmatic Clinical Studies initiative in 2014. Pragmatic clinical studies allow for larger-scale studies with longer timelines to compare the benefits and harms of two or more approaches known to be effective for preventing, diagnosing, treating, or managing a disease or symptom. They focus on everyday care for a wide range of patients. This research project is one of the studies PCORI awarded as part of this program.

This research project is in progress. PCORI will post the research findings on this page within 90 days after the results are final.

What is the research about?

The appendix is a small sac at the bottom of the large intestine. Appendicitis is a health problem that occurs when this sac becomes inflamed. Appendicitis can cause pain, fever, and even death. People have a 1 in 10 chance of getting appendicitis in their lifetime.

Appendicitis can be treated with surgery or with antibiotics. In the United States, doctors almost always treat appendicitis with surgery. Studies from Europe show that in most patients, antibiotics alone are safe and work well to treat appendicitis. However, about 1 in 4 people who start treatment with antibiotics end up needing surgery.

In this study, the research team wants to see if treating patients with antibiotics is as effective as surgery. If it is, some patients may prefer treatment with antibiotics. The team is comparing quality of life, health effects, hospitalization, and number of follow-up doctor visits for patients who use antibiotics and those who have surgery.

Who can this research help?

Findings from this study may help doctors and patients decide whether to treat appendicitis with surgery or antibiotics.

What is the research team doing?

The research team is recruiting 1,552 patients with appendicitis at hospitals in eight states. They are assigning the patients, by chance, to two groups. Patients in the first group receive intravenous, or IV, antibiotics for at least 24 hours, followed by oral antibiotics, for a total of 10 days of antibiotic therapy. Patients in the second group have surgery to remove the appendix. Four weeks after treatment, the research team is asking patients in both groups about their symptoms; pain level; quality of life; and how fast they return to daily activities, work, or school. The team is also following up with patients for two years after treatment to see which group got better faster and is asking how often patients had harms from treatment.

The research includes an extra 500 patients who did not want to participate in the main part of the study: 250 patients who choose surgery and 250 who choose antibiotics. The research team wants to know whether people who choose their treatment have different experiences with treatment than the patients who agree to participate in the main study.

A group of patient advisors and healthcare quality staff from each hospital are working with the research team to plan the study and analyze the results.

Research methods at a glance

Design Elements Description
Design Randomized controlled trial
Population English- or Spanish-speaking adults ages 18 and older with a clinical diagnosis of acute uncomplicated appendicitis
  • Guidelines-based treatment with IV antibiotics for 24 hours, followed by oral antibiotics for 9 days
  • Appendectomy using open or laparoscopic approach

Primary: quality of life

Secondary: days until resolution of appendicitis symptoms, perforated appendicitis, complications from treatment, appendiceal cancer, number of hospital days, days using antibiotics beyond initial treatment schedule, clinic visits, patient-reported overall mental and physical health, gastrointestinal quality of life, decisional regret

Timeframe 4-week follow-up for primary outcome

Engagement Resources

More About This Research

Click for larger version
(Credit: CODA Study team)


PCORI-Funded Study Examining Treatment Options for Appendicitis Yields Useful Early Results
A PCORI-funded study comparing surgery versus antibiotics for uncomplicated appendicitis has released early results that physicians and patients can use when weighing treatment options, especially during the coronavirus pandemic.

Study Website

CODA Appendicitis Study
University of Washington

Stories and Videos

Media Mentions

Behind The Knife: The Surgery Podcast (October 5, 2020)
In this episode, Principal Investigator David Reed Flum, MD, MPH, and members of his team discuss the early results of the trial.
Listen on Apple Podcasts / Spotify

Project Information

David Reed Flum, MD, MPH
University of Washington
Comparing Outcomes of Drugs and Appendectomy (CODA)

Key Dates

August 2015
June 2022

Study Registration Information


Has Results
Project Status
Award Type
Health Conditions

Health Conditions

These are the broad terms we use to categorize our funded research studies; specific diseases or conditions are included within the appropriate larger category. Note: not all of our funded projects focus on a single disease or condition; some touch on multiple diseases or conditions, research methods, or broader health system interventions. Such projects won’t be listed by a primary disease/condition and so won’t appear if you use this filter tool to find them.

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PCORI is interested in research that seeks to better understand how different clinical and health system options work for different people. These populations are frequently studied in our portfolio or identified as being of interest by our stakeholders.

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Funding Opportunity Type
Intervention Strategy

Intervention Strategies

PCORI funds comparative clinical effectiveness research (CER) studies that compare two or more options or approaches to health care, or that compare different ways of delivering or receiving care.

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Research Priority Area


The state where the project originates, or where the primary institution or organization is located.

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Last updated: January 7, 2022