Experts revise guidelines for irritable bowel syndrome
Irritable bowel syndrome (IBS) is a chronic disorder characterized by recurrent bouts of constipation, diarrhea, or both, as well as abdominal pain, bloating, and gas. IBS is a functional disorder, which means that it’s not attributable, as far as we know, to any underlying disease process or structural abnormality. It’s thought to involve various, often interacting, factors — infection, faulty brain-gut communication, heightened pain sensitivity, hormones, allergies, and emotional stress.
The good news is that IBS doesn’t increase the risk for more serious conditions, such as ulcerative colitis or colon cancer. On the other hand, a disorder resulting in (at best) annoying and (at worst) debilitating and worrisome symptoms with no known cause can be difficult to diagnose and treat, not to mention live with. Managing IBS typically involves some trial and error, which can be challenging for patients and clinicians alike. Various tests or procedures may be ordered to rule out other conditions. Many diverse therapies, not all of them proven, are used in treating the symptoms, including antibiotics, antispasmodics, antidepressants, dietary changes, relaxation techniques, and psychotherapy, as well as drugs to relieve constipation and diarrhea.
Guidelines from the American College of Gastroenterology (ACG) may aid in the search for effective IBS management strategies. Written by an expert panel of ACG gastroenterologists and published as a supplement to the January 2009 issue of The American Journal of Gastroenterology, the recommendations update the ACG’s first statement, which was published in 2002. The new guidelines incorporate the latest evidence on newer therapies, such as probiotics and certain IBS-specific drugs, as well as older treatments.
According to the 2009 recommendations, extensive testing (complete blood count, thyroid function test, stool testing for parasites, and abdominal imaging) is unnecessary for people with typical IBS symptoms who have no family history of colon cancer, inflammatory bowel disease, or celiac sprue — and no “alarm symptoms,” including rectal bleeding, weight loss, or iron-deficiency anemia.
The guidelines also simplify the language used to describe IBS. Previous criteria incorporated a list of specific symptoms (stool consistency and frequency, for example) that the task force concluded had limited value in identifying IBS. The disorder is now defined simply as “abdominal pain or discomfort that occurs in association with altered bowel habits over a period of at least three months.”
The panel reviewed 300 studies on the natural course, diagnosis, and treatment of IBS and developed a series of recommendations, graded as strong (1) or weak (2) — with the underlying evidence rated as strong (A), moderate (B), or weak (C). Here are some highlights:
Antibiotics. Short-term use of rifaximin (Xifaxan), a nonabsorbable antibiotic (one that stays in the gut), helps reduce overall symptoms, especially bloating (grade 1B). Its long-term safety and effectiveness are uncertain, and it is not yet approved for IBS. Note: Rifaximin is very expensive.
Bulking agents and fiber. Bulking agents that contain psyllium (ispaghula husk) — for example, Metamucil, Fiberall, Hydrocil, and Konsyl — improve overall symptoms, but neither wheat bran nor corn bran is better than a placebo in managing IBS (grade 2C).
FDA-approved IBS drugs. The newest IBS drug, lubiprostone (Amitiza), is effective in relieving overall symptoms of women with constipation-predominant IBS (grade 1B). Alosetron (Lotronex) is effective in relieving symptoms of women with diarrhea-predominant IBS (grade 2A), but its availability and use are limited because it’s been linked to severe constipation and ischemic colitis. Tegaserod (Zelnorm) helps relieve overall symptoms of women with constipation-predominant IBS (grade 1A) — and in both men and women with mixed IBS (grade 1B).
Antispasmodics. Hyoscine, cimetropium, and pinaverium — all unavailable in the United States — as well as peppermint oil may provide short-term relief of abdominal pain (grade 2C), but not much is known about their long-term value or safety.
Psychological therapies. Twenty randomized controlled trials have shown that psychological therapies, including cognitive therapy, dynamic psychotherapy, and hypnotherapy — but not relaxation therapy — are more effective than usual care in relieving overall symptoms (grade 1B).
Probiotics. Research is difficult because there are many strains of probiotics, and preparations and doses vary. Lactobacilli alone apparently don’t relieve IBS symptoms, but certain combination products help (grade 2C). Bifidobacteria, another kind of intestinal flora, may also be effective (2C).
Antidepressants. Tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) are effective in relieving overall symptoms and reducing abdominal pain, but not much is known about their safety and tolerability in people with IBS (grade 1B).
April 2009 update
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