How to recruit ulcerative colitis and Crohn's patients for clinical trials

How many Americans have IBD?

A 2023 study in Gastroenterology led by James Lewis estimated IBD prevalence at 721 per 100,000 people, or about 2.39 million Americans diagnosed with ulcerative colitis or Crohn's disease when applied to the 2020 census population (Lewis et al., Gastroenterology 2023).

A simple ratio puts the competition in perspective. The Lewis study reports 2,390,000 Americans diagnosed with IBD. Divided across 156 recruiting studies, that is roughly 15,321 people per study nationally, before eligibility criteria, geography, and patient willingness cut the pool down. Most of those patients will never hear about a trial unless a physician brings it up.

IBD trials look different from most conditions on this list. 68 of 127 recruiting interventional trials are industry funded, and the typical industry trial lists 19.5 US locations, more than most other conditions here. Many community gastroenterology practices run IBD studies themselves, so a referring practice may also be a competitor. Be clear about which study you are asking about and why your site is convenient for the patient.

How many ulcerative colitis and Crohn's disease trials are recruiting in the United States right now?

As of October 6, 2026, ClinicalTrials.gov lists 156 ulcerative colitis and Crohn's disease studies with a status of recruiting and at least one location in the United States (ClinicalTrials.gov). Of those, 127 are interventional trials and 29 are observational studies. Industry is the lead sponsor on 74 of them, about 47%. Academic centers, cooperative groups, and government sponsors run the rest.

Interventional ulcerative colitis and Crohn's disease trials by phase:

The median interventional trial targets 110 participants in total across all of its sites. The typical industry funded trial lists 19.5 recruiting locations in the United States, so each site is usually expected to deliver a small slice of that total, and sponsors notice quickly which sites deliver none.

Where are ulcerative colitis and Crohn's disease trials concentrated?

Every location on every recruiting study counts here. Together the 156 studies list 2,172 recruiting US locations. These states host the most recruiting studies:

The most frequently listed institutions include Peak Gastroenterology Associates, Tyler Research Institute,, University Gastroenterology, and Boston Children's Hospital. The industry sponsors with the most recruiting ulcerative colitis and Crohn's disease trials right now include Takeda, Eli Lilly and Company, Janssen Research & Development,, AbbVie, and Sanofi. If your site sits in one of the top states, you are recruiting from the same patient population as several large academic programs at once, and the patients who reach you will mostly come through the physicians who already treat them.

Which physicians manage IBD patients?

• Gastroenterologists, who diagnose by colonoscopy and manage nearly all patients on advanced therapy. The AAMC counts 17,219 active gastroenterologists (AAMC 2024 via Becker's).
• Pediatric gastroenterologists, for pediatric and adolescent studies.
• Colorectal surgeons, for postoperative Crohn's and pouch studies.
• Primary care physicians, who see the symptoms before the diagnosis.

What decides eligibility in IBD trials?

Most IBD trials enroll patients with moderately to severely active disease, confirmed by endoscopy and scored with a disease activity index, and they specify which advanced therapies a patient may or may not have tried. The gastroenterologist knows all of this. A summary that says, for example, "moderate to severe UC with an inadequate response to at least one advanced therapy" lets the practice pull candidates from its own records. Screen failures average 36.3% across Phase 2 and 3 trials (Tufts CSDD), and endoscopy confirmation is a common failure point, so ask for the most recent colonoscopy report.

Why physician referral matters more than volume

A large patient population does not fill trials on its own. Physicians refer a median of about five patients into clinical trials per year, which is less than 0.2% of their annual patient volume (Getz, Applied Clinical Trials). In Tufts CSDD research, physicians and nurses named lack of access to study information and lack of time as the main reasons they do not refer, and physicians in clinical practice were 2.7 times more likely to refer than physicians in hospital settings (Tufts CSDD via Applied Clinical Trials).

That is the gap a site can close. The physicians who diagnose and manage your study population already know which patients are likely to qualify. They need a short, specific summary of your open study, a named coordinator, and a reason to believe the patient will come back to them.

A practical ulcerative colitis and Crohn's disease referral plan for your site

1. Pull the live ClinicalTrials.gov list for your state and note which competing studies are enrolling the same population within driving distance of your site.
2. List the gastroenterologists and colorectal surgeons within a realistic drive of your site. Community practices come first.
3. Send each physician a one page study summary: the diagnosis, the two or three criteria that decide most eligibility, what the patient will experience, and the coordinator's direct line.
4. Follow up by email and LinkedIn, and call the practices that engage.
5. Report back to the referring physician on every patient, whether or not the patient enrolls.

See how to get physicians to refer patients and the referral letter guide for templates.