Irritable Bowel Syndrome Management Reviewed

Laurie Barclay, MD

December 22, 2008

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December 22, 2008 — The American College of Gastroenterology Irritable Bowel Syndrome (IBS) Task Force developed a monograph reviewing the epidemiology, diagnostic approach, and available and emerging treatments of IBS. This evidence-based review, which represents an update from the 2002 Monograph on IBS including new data, is published in a January 1, 2009, supplement to the American Journal of Gastroenterology.

"...IBS is characterized by abdominal discomfort associated with altered bowel function; structural and biochemical abnormalities are absent," write Lawrence J. Brandt, MD, MACG, from Montefiore Medical Center in Bronx, New York, and colleagues from the American College of Gastroenterology IBS Task Force. "The pathophysiology of IBS is multifactorial and of intense recent interest, largely because of the possibility of developing targeted therapies. As IBS is one of the most common disorders managed by gastroenterologists and primary care physicians, this monograph was developed to educate physicians about its epidemiology, diagnostic approach, and treatments."

The task force authors describe IBS as a common condition associated with abdominal pain and changed bowel habit for 3 months or more. Based on a series of systematic reviews to evaluate the diagnostic yield of various investigations and the efficacy of available treatments of IBS, the task force made the following recommendations:

  • In young patients without alarm features, IBS can be diagnosed clinically, and additional investigations such as laboratory tests are not needed. However, serologic testing for celiac sprue may be helpful in some patients, particularly those with diarrhea-predominant and mixed diarrhea-constipation IBS.

  • In patients older than 50 years and in those with alarm features, additional investigation such as colonoscopy is recommended.

  • Although the quality of the evidence is poor, trials to date suggest that psyllium fiber, certain antispasmodics, and peppermint oil are effective in patients with IBS. Psyllium may alleviate global IBS symptoms, whereas peppermint oil may alleviate abdominal pain for the short term.

  • Although available evidence from trials thus far suggests that some probiotics may be effective in relieving overall IBS symptoms, more studies are needed. Lactobacilli alone do not appear effective in reducing IBS symptoms, but limited evidence suggests that probiotic combinations may reduce symptoms.

  • Antidiarrheal agents such as loperamide have been shown to decrease stool frequency but do not affect pain or the overall symptoms of IBS.

  • In patients with diarrhea, 5-hydroxytriptamine 3 antagonists such as alosetron are effective, based on good-quality evidence. Because of the risk for ischemic colitis, however, patients should be carefully selected. In patients with diarrhea-predominant IBS, alosetron is more effective vs placebo in reducing IBS symptoms, but it is associated with ischemic colitis at a rate of approximately 1 case for every 1000 patient-years of alosetron use.

  • In patients with constipation, 5-hydroxytriptamine 4 agonists such as tegaserod are modestly effective, based on good-quality evidence. However, the possible risk for cardiovascular events linked to these agents limits their usefulness. In women with constipation-predominant IBS and in patients with mixed diarrhea-constipation IBS, tegaserod effectively reduces global IBS symptoms, but it is linked to increased diarrhea in 1% to 2% of patients and serious cardiovascular complications in 0.11% of patients.

  • In patients with any of the IBS subtypes, tricyclic antidepressants and selective serotonin reuptake inhibitors have been shown to be effective in alleviating abdominal pain and global symptoms. The quality of evidence supporting the usefulness of these drugs was graded as moderate because the trials were generally of good quality, but the overall number of patients enrolled meant that additional evidence could change the confidence in the estimate of effect. Safety and tolerability data for these medications in patients with IBS are limited.

  • Particularly in diarrhea-predominant IBS, nonabsorbable antibiotics are effective, with a moderate quality of evidence.

  • In constipation-predominant IBS, selective C-2 chloride channel activators such as lubiprostone are effective, based on a moderate quality of evidence. In women with constipation-predominant IBS, lubiprostone has been shown to be more effective vs placebo.

  • Psychological therapies may be beneficial to patients with IBS. However, the quality of evidence is poor. Global IBS symptoms may be relieved with cognitive therapy, dynamic psychotherapy, and hypnotherapy, but relaxation therapy does not appear to be as effective.

 

"Our expanding knowledge of the pathogenesis of IBS has led to the identification of a wide variety of novel therapeutic agents," the task force authors write. "Broadly speaking, there are agents in development for IBS with predominantly peripheral effects and some with both peripheral and central effects. Examples of classes of drugs with predominantly peripheral effects include agents that affect chloride secretion, calcium channel blockers, opioid receptor ligands, and motilin receptor ligands, [whereas] drug classes which exert effects both peripherally and centrally include novel serotonergic agents, corticotropin-releasing hormone antagonists, and autonomic modulators."

Am J Gastroenterol. 2009;104(suppl 1):S1-S34.

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