Ulcerative Colitis and Crohn’s Sing Different Tunes

Differences have important consequences for treatment strategies

It’s not rare for a patient to be told they have ulcerative colitis only to later find out that they instead have Crohn’s disease.

“It’s difficult for doctors to make a proper diagnosis sometimes because Crohn’s can look very similar to ulcerative colitis,” Dr. Giovanni Monteleone, a gastroenterologist at the University of Rome Tor Vergata, said.

Shared characteristics include diarrhea and abdominal pain caused by inflammation of the digestive tract, but the location of this inflammation differs. In ulcerative colitis, inflammation only affects the large intestine, starting with the rectum—which is located in the lower left abdomen. Meanwhile, Crohn’s disease most commonly involves the terminal ileum—located in the lower right abdomen—although it can affect the entire gastrointestinal tract as well.

Crohn's Disease vs. Ulcerative Colitis

And while ulcerative colitis works its way from the rectum through the colon continuously, Crohn’s disease can cause patches of inflammation surrounded by healthy spots. That patterning can only be identified through a colonoscopy to view the inner lining of the large intestine. Even with this invasive test, about 10 percent of cases are still unclear.

Genetic studies are no help in the matter. “The genetic alterations associated with these diseases are common to both,” Monteleone said. “So we have no genetic diagnostic test to single out a colitis or Crohn’s diagnosis.”

What’s left, then, is simply time. “In those cases, the patient will eventually be diagnosed with one disease or the other as evidence mounts,” Dr. Guillermo Rossiter, senior director of Inflammation and Immunology R&D at Celgene, said.

We have a long way to go in terms of helping the most patients with medical therapies.

For instance, some patients develop anal fistula and fissures—areas of tunneling and painful cracks in the skin around the anus. “That’s a sign that we’re dealing with Crohn’s disease and not colitis,” said Dr. Faten Aberra, a gastroenterologist at the University of Pennsylvania and a committee member at the Crohn’s & Colitis Foundation of America.

At this year’s Annual Scientific Meeting of the American College of Gastroenterology (ACG) in Honolulu, researchers are discussing ways to improve both the diagnosis and treatment of these diseases.

Today, for instance, scientists are looking at how antibodies in a patient’s blood and urine can be used to differentiate these diseases. At ACG, researchers will discuss how symptoms outside the digestive tract can be used to tell these diseases apart.

With the proper diagnosis, doctors can then select the best treatment, from medical options—such as steroids, immunosuppressants and biologics—to more severe surgical procedures to remove diseased sections of the bowels. While up to 75 percent of ulcerative colitis patients will respond to medications, 70 percent of Crohn’s disease patients will undergo surgery.

Even the medical treatment options are far from ideal. “Steroids, immunosuppressants and biologics both have unattractive safety profiles, and patients often become less responsive to biologics over time,” Rossiter said.

New ways to treat inflammatory bowel diseases will of course also be a topic of conversation at ACG. Although medical and surgical treatment can help ease some of the symptoms, none targets the root causes. And there are no cures.

“We need something else to improve the quality of life of these patients,” Monteleone said. “These are nasty conditions that affect their lives; they stay home for long times, cannot work, cannot spend time with their relatives because of their quality of life and hospitalizations.”

Patients have reasons to be hopeful, though, as new treatment options are being developed. And the recent recognition of both Crohn’s and ulcerative colitis as orphan diseases by the U.S. Food and Drug Administration should help expedite the development of several therapies currently in clinical trials.

“We have a long way to go in terms of helping the most patients with medical therapies,” Aberra said. “We can get some patients into remission, but some do not respond at all; we still need to figure out which patients will respond to which medicine.”