ORLANDO — A recommendation for antibiotic therapy to combat bacterial overgrowth, a stronger recommendation for antidepressants to ease symptoms, and serum testing for celiac disease are forthcoming updates to the American College of Gastroenterology's irritable bowel syndrome guidelines.
New recommendations on the diagnosis of irritable bowel syndrome (IBS) are also expected in the updated guidelines, which the college plans to publish in January 2009, with an earlier release online.
The guidelines also will recommend the addition of microscopic colitis to the differential diagnosis of IBS. This addition is based on a prospective, multicenter study that found 4% of 454 people suspected of IBS actually had microscopic colitis.
“This is definitely new … and potentially a very, very important message from this document,” Dr. William D. Chey said during a media briefing at the annual meeting of the American College of Gastroenterology.
“If a patient has diarrhea-predominant IBS and undergoes colonoscopy, it is reasonable to consider taking random biopsies to exclude microscopic colitis,” said Dr. Chey, who is professor of medicine at the University of Michigan, Ann Arbor.
Updated diagnosis recommendations will be reassuring for many clinicians, he said. “Doctors are uncomfortable with assigning a diagnosis of IBS. They are worried that they are missing something else” such as colon cancer, ulcerative colitis, or Crohn's disease.
“The reassuring bit of information that comes out of our analysis … is that the likelihood of a person who has IBS symptoms and no warning signs having some other organic diagnosis such as colon cancer, inflammatory bowel disease, or thyroid disease is no greater than in the general population,” he continued. “Although I understand why it's a concern, it is not an entirely rational concern.”
Doctors in clinical practice often characterize people with only abdominal pain as having IBS, he added. “These recommendations, based on the best available evidence, apply to people with pain and altered bowel habits.”
The link between pain and bowel disturbance is very close, Dr. Nicholas J. Talley said. “They have pain, they pass stool and get relief—that is IBS. It's absolutely obvious to me.” Dr. Talley is chair of the department of internal medicine at the Mayo Clinic, Jacksonville, Fla.
Because of a greater risk of organic disease, patients who present with IBS symptoms plus other warning signs such as unexplained weight loss, GI bleeding, or a family history of colon cancer, inflammatory bowel disease, or celiac sprue require a more detailed evaluation, Dr. Chey said.
Another new recommendation is for use of a “nonabsorbable antibiotic” to relieve IBS symptoms. The only approved antibiotic that remains in the gut to alter flora without systemic absorption is rifaximin (Xifaxan), now under investigation as a treatment for IBS. Rifaximin was found to be superior to placebo for improvement of IBS symptoms, especially bloating, in recent studies (Ann. Pharmacother. 2008;42:408–12; Adv. Med. Sci. 2007;52:139–42).
“What is uncertain is how long the symptom relief lasts and what you should do if the symptoms recur,” said Dr. Philip S. Schoenfeld, a gastroenterologist at the University of Michigan, who also spoke at the media briefing.
“There is evidence of benefit in the short term [with rifaximin]. It is critical that you know that,” Dr. Talley commented. He predicted this recommendation will be controversial because IBS is chronic and antibiotics are typically prescribed acutely.
Dr. Schoenfeld said that physicians may be concerned about increasing antibiotic resistance if the agents are given to thousands of IBS patients.
There is a greater focus on the use of antidepressants to treat IBS in the new guidelines.
“There is a stronger recommendation that tricyclic antidepressants, used in low doses before people go to sleep at night, are an effective medicine for irritable bowel syndrome,” Dr. Schoenfeld said. The agents can reduce bloating and discomfort by altering brain-gut signaling about motility and distention. He added that constipation, a side effect of tricyclic antidepressants, is actually beneficial in this population.
The authors of the guidelines also found enough evidence to support SSRIs for symptom improvement. “I want to emphasize that this does not appear to be related to depression,” Dr. Talley said. “This appears to be related to effects of these drugs either in the brain or the gut, but probably both places.”
Some treatment recommendations in the guidelines are not expected to change, such as those for treatment with loperamide (Imodium) or alosetron (Lotronex).
The new recommendation for serologic celiac disease testing is for a subset of IBS patients. “We made a much stronger recommendation for testing for celiac disease in patients with diarrhea-predominant or mixed IBS,” Dr. Chey said. “We actually came out and said serologic screening for celiac disease should be pursued.”