British guidelines for chronic diarrhea in adults

Reference

Arasaradnam RP, Brown S, Forbes A, et al. Guidelines for the investigation of chornic diarrhoea in adults: British Society of Gastroenterology, 3rd edition. Gut 2018;67(8):1380-1399.

Synopsis

Let's just say it: The British do good guidelines. This is an evidence-based guideline that was generated after a thorough search; included a range of physicians, nurses, and patients; and followed the AGREE framework for creating trustworthy guidelines. Chronic diarrhea is defined as "the persistent alteration from the norm with stool consistency between types 5 and 7 on Bristol stool chart and increased frequency greater than 4 weeks duration," where Bristol 5 is soft blobs with clear-cut edges passed easily and Bristol 7 is entirely liquid. Here are the key recommendations for the evaluation of adults with chronic diarrhea: (1) Perform a detailed history and physical, and order a complete blood count (followed by ferritin if anemic), a thyroid-stimulating hormone test, and serology for celiac disease (tissue transglutaminase or antiendomysium). (2) Test stool for Clostridium difficile, ova and parasites, and calprotectin (abnormal inflammatory bowel disease), and consider a fecal immunochemical test. (3) In patients with altered bowel habits, rule out colorectal cancer with colonoscopy. In patients without frank rectal bleeding, order fecal immunochemical testing to exclude cancer. (4) If symptoms persist, refer for further investigation. (5) Further testing could include hydrogen breath test for lactose intolerance, video capsule endoscopy, fecal elastase testing for fat malabsorption, tests for bile acid diarrhea, and magnetic resonance imaging for the evaluation of chronic pancreatitis. The authors of the guideline advocate early testing for celiac disease, which may be more appropriate in a referral population and in the United Kingdom where the blood test is likely less expensive; its use as a screening test or in a low prevalence population would have a low positive predictive value.