CHICAGO — All irritable bowel syndrome patients with the diarrhea and mixed diarrhea-constipation phenotypes should be screened for celiac disease, according to guidelines issued by the American College of Gastroenterology earlier this year.

The guidelines were developed in response to emerging evidence showing a three- to fourfold greater prevalence of celiac disease in IBS patients than in the general population, Dr. William D. Chey said at a meeting on celiac disease sponsored by the American Gastroenterological Association.

Celiac disease and IBS can have virtually identical symptoms, and mistaking one for the other or not knowing that both are present, can lead to expensive, unnecessary tests, ineffective therapies, and pointless repeat visits, said Dr. Chey, professor of internal medicine and director of the gastrointestinal physiology laboratory at the University of Michigan, Ann Arbor.

“Most important, people with untreated celiac disease have higher mortality and are at higher risk of developing cancer, osteoporosis, and a variety of other metabolic abnormalities than people who have been treated. There are clear cost consequences of not doing this correctly, but there are even more profound health consequences for the patients who are incorrectly diagnosed and treated,” said Dr. Chey, co–editor in chief of the American Journal of Gastroenterology.

A systematic review by Dr. Chey and his colleagues of seven studies from around the world involving 2,978 people (1,052 with IBS) found that 3% of the IBS cohort versus 0.7% of controls were positive for antiendomysial antibody (EMA), tissue-transglutaminase antibody (tTG), or both (odds ratio 2.94, 95% confidence interval 1.36-6.35). In a separate analysis of five studies, 3.6% of IBS patients (34 of 952) versus 0.7% of controls (12 of 1,798) tested positive for EMA, antigliadin antibody, or tTG and showed small bowel biopsy evidence of celiac disease (OR 4.34, 95% CI, 1.78-10.6) (Arch. Intern. Med. 2009;169:651-8; Am. J. Gastroenterol. 2009;104[suppl1]:S1-35).

There are limited data on this issue from the United States. Dr. Chey cited a retrospective study (Am. J. Gastroenterol. 2008;103[suppl 1]:S472) and a prospective study (Gastroenterology 2007;132:A-147) that found only small absolute differences in celiac disease prevalence among IBS patients versus controls, and the differences did not reach statistical significance in either study.

However, the patient populations in these studies were relatively small. “If we had a larger study, those differences probably would be significant. We had about 500 IBS patients [in the prospective study], but for those types of differences we would need an even larger study.”

Two decision analytic models used as a basis for the ACG guidelines showed that serologic screening for celiac disease in the IBS patient population is cost effective, even though the disease's prevalence among IBS patients actually is low, Dr. Chey said. According to these models, screening is cost effective as long as disease prevalence exceeds 1%, and both the prospective and retrospective studies from the United States met that criterion.

“It sounds impressive to say there's a three- to fourfold increase, and that is true, but overall, the prevalence of celiac disease among IBS patients is still pretty low,” Dr. Chey emphasized. “It's really important for doctors to understand that they're only going to find celiac disease in 1 or 2 out of 100 patients.

They're going to do a lot of testing and not find a lot of celiac disease. However, the benefits to patients and the time and costs saved with an accurate diagnosis and appropriate care make this routine testing worthwhile,” he said.

At present, the ACG guidelines do not recommend screening for celiac disease in constipation-predominant IBS patients because there are “virtually no data” showing that these patients are at increased risk, Dr. Chey said. “We didn't feel comfortable making a sweeping recommendation. It may be reasonable to screen in this population, but we need prospective data.” The guidelines have been published in the American Journal of Gastroenterology (2009;104 ([suppl 1]):S1-35).

Dr. Chey also reported recent findings regarding patients who develop gastrointestinal symptoms related to the ingestion of gluten who do not have celiac disease. Some of these patients have a sensitivity to gluten, but in many cases do not show the intestinal inflammation on biopsy that is the hallmark of celiac disease, or they have mild abnormalities on biopsy but totally normal serology.

“The days of dismissing patients who say they have reactions to certain foods in their diets—particularly gluten-containing foods—are over. There is this other condition out there, and we need to understand it,” said Dr. Chey, adding that the prevalence of gluten sensitivity could be three or four times that of celiac disease.

“This is a rapidly expanding area and there are groups starting to work hard on understanding gluten sensitivity,” he said.

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'There are … profound health consequences for the patients who are incorrectly diagnosed and treated.'

Source DR. CHEY

Guidelines Call for Celiac Screening in IBS