Project Summary

PCORI has identified the need for large studies that look at real-life questions facing diverse patients, caregivers, and clinicians. In 2014, PCORI launched the Pragmatic Clinical Studies initiative to support large-scale comparative effectiveness studies focusing on everyday care for a wide range of patients. The Pragmatic Clinical Studies initiative funded this research project and others.

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?

Diverticulitis occurs when pouches in the digestive tract become inflamed. Patients have symptoms such as pain, fever, and nausea. Some patients only have one episode, but the problem can come back. Guidelines for treating this health problem recommend that doctors work with each patient to choose a treatment.

One treatment option is surgery. Surgery lowers the risk of repeat episodes and can relieve symptoms. But surgery has risks such as bleeding, infection, or harm to nearby organs.

Another treatment option is medical management. In this approach, patients manage symptoms through diet, exercise, and supplements such as fiber. A doctor may also prescribe antibiotics. Medical management is less invasive and safer than surgery. It can improve symptoms, but it may not prevent repeat episodes.

In this study, the research team is comparing the effect of diverticulitis treatment with surgery or medical management on patients’ quality of life.

Who can this research help?

Results may help doctors and patients when considering ways to treat diverticulitis.

What is the research team doing?

The research team is enrolling 500 patients with diverticulitis. The team is assigning patients by chance to receive initial treatment with surgery or medical management. For patients assigned to receive surgery, surgeons remove the diseased part of the colon. Patients assigned to medical management view a video that explains strategies such as diet, exercise, medicine, and supplements.  

The research team is asking patients about their quality of life at the start of the study and again 6, 9, and 12 months later. Also, the team is looking into

  • How patients feel about their treatment decision
  • How productive patients are at work
  • If patients had any life-threatening side effects from treatment
  • Patients’ healthcare use

The research team is comparing these outcomes between those who receive surgery and those who receive medical management. They are also comparing results with 200 patients who had surgery or medical management, who were not assigned to one of these options by chance.

Patients with diverticulitis, surgeons, and leaders of professional societies are helping to design the study.

Research methods at a glance

Design Element Description
Design Randomized controlled trial
Population 500 adults with at least one episode of diverticulitis confirmed by CT scan in last 5 years and a colonoscopy to rule out other colon pathology and (1) history of recurrent uncomplicated diverticulitis without current symptoms during the past 5 years, or (2) persistent signs, symptoms, and concerns related to diverticular disease ≥3 months after recovery from an episode of diverticulitis 
  • Partial colectomy
  • Medical management

Primary: gastrointestinal quality of life

Secondary: diverticulitis quality of life, decisional regret, work productivity, serious adverse events related to diverticulitis treatment, healthcare utilization related to diverticulitis

Timeframe 1-year follow-up for primary outcome

Project Information

David Flum, MD, MPH
University of Washington
Comparison of Surgery and Medicine on the Impact of Diverticulitis (COSMID) Trial

Key Dates

November 2018
January 2026

Study Registration Information


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. View Glossary
Populations Populations 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. View Glossary
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. View Glossary
State State The state where the project originates, or where the primary institution or organization is located. View Glossary
Last updated: March 14, 2024