Ulcerative Colitis Disease Activity Index (UCDAI)

The UCDAI is a measurement that is often used in clinical trials for IBD

Clinical researcher
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Research is an important part of developing new treatments for every disease, including inflammatory bowel disease (IBD). Research often means testing new drug formulations in a small group of patients, in order to determine if it should be tested on a large group, or if the idea should be reformulated or abandoned altogether. There are laws and protocols surrounding the testing of new drugs in patients—it's not something that is done without significant oversight.

Usually, the drug has already been tested first in computer models, and then on animals (usually rats or mice), and then in healthy individuals. In many clinical trials, an independent scale is used to track progress, and one such scale for ulcerative colitis is the Ulcerative Colitis Disease Activity Index (UCDAI). 

How Do Researchers Know If a Treatment Is Working?

In order to determine if a treatment for IBD is effective, scientists often use a specialized scale to measure disease activity in individual patients. Disease activity might include such signs as pain, how many times a person has gone to the bathroom in a day, or even inflammation in the colon that is found when a doctor completes a colonoscopy. In some cases, extra-intestinal markers of disease, like skin, eye, or joint problems, could also be included in the analysis.

What a specialized scale does is give the researchers a common language to talk about how each patient is doing while receiving the treatment being tested.

These specialized scales may or may not be used by gastroenterologists in clinical practice, outside of a clinical trial. Most of the time, they are not, because it doesn't necessarily achieve anything: physicians wouldn't compare one patient's score against another patient's score, so the results would not be helpful.

A clinical scale is generally only useful when comparing patients who are receiving the same intervention (such as a medication) over a period of time under similar circumstances. Additionally, it might be too difficult and time-consuming to do the scoring for all patients, especially when there's no proven gain to doing it. However, in some cases, it might be used to track disease activity in patients who are starting a new treatment.

The Ulcerative Colitis Disease Activity Index

For ulcerative colitis, there are several different scoring scales that are used for the purposes of clinical research. One that is used fairly often is called the UCDAI. It goes by other names at times, and might also be called the Sutherland Index or the Modified Ulcerative Colitis Disease Activity Index. The UCDAI was developed in 1987 by Sutherland, et al. The UCDAI would be given at the beginning of a clinical trial to ascertain a baseline, and then again at specified points throughout the trial.

The UCDAI is a series of qualifiers about the symptoms of ulcerative colitis including stool frequency, rectal bleeding, the appearance of the lining of the colon, and a physician rating of disease activity. Each of these items is given a number from 0 to 3, with 3 being the highest rating for disease activity.

Some of the questions require a physician to do an endoscopy and see the colon, so it is not a scale that can be used by a patient to understand how their disease is progressing.

For the purpose of clinical trials, remission is often defined as a UCDAI score of 1 or less, and improvement is a reduction of 3 or more points from the score at the beginning of the trial.

A Word From Verywell

The UCDAI, or any other disease activity scale, cannot tell a person whether or not he or she has ulcerative colitis, or what the status of the disease is. It is a tool that is used by researchers, often during the course of clinical trials to study the effects of a new medication.

Many gastroenterologists don't use this scale, so it isn't something that you should expect to be part of a standard assessment for IBD.


Sutherland LR, Martin F, Greer S, et al. "5-Aminosalicylic Acid Enema in the Treatment of Distal Ulcerative Colitis, Proctosigmoiditis, and Proctitis." Gastroenterology 1987;92:1894–1898. 5 Oct 2010.

Also Known As: Sutherland Index, Modified Ulcerative Colitis Disease Activity Index