Irritable Bowel Syndrome (IBS)

Background

• Irritable bowel syndrome (IBS) is characterized by chronic and/or recurrent abdominal pain or discomfort and altered bowel habits.
• IBS has an estimated worldwide prevalence of 14% in women and 9% in men, and usually occurs before age 50 years.
• There is no definitive etiology, but pathophysiology may include visceral hypersensitivity, central desensitization, dysbiosis, immune dysfunction, gut barrier dysfunction, dysmotility, and hormonal determinants.
• IBS symptoms may be precipitated by infection, fluctuate over years, overlap with other functional gastrointestinal disorders, and be exacerbated by stress. While generally a benign condition, IBS can be complicated by depression and anxiety with a significant effect on quality of life.

Evaluation

• Diagnose irritable bowel syndrome (IBS) if abdominal pain or discomfort occurs on average at least 1 day/week for at least 6 months since onset and meets at least 2 of the following 3 criteria: pain changes with defecation, changes occur in bowel frequency, and/or changes occur in stool appearance (form).
• Order tests at initial presentation to assess for conditions warranting further investigation including complete blood count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) to rule out inflammatory conditions warranting investigation (Strong recommendation). If diarrhea is present and particularly so in a patient < 45 years old, consider fecal calprotectin or lactoferrin (Weak recommendation).
• Consider antibody testing for celiac disease (Weak recommendation).
• Evaluate for alarm features (weight loss, rectal bleeding, anemia, mass, family history of colon or ovarian cancer, age > 60 years old with change in bowel habits) which indicate a need for testing for serious disease.
  • Perform colonoscopy if > 45 years old or alarm features suggesting increased risk for colorectal cancer (Strong recommendation).
  • Do not perform extensive testing for patients without alarm features who meet symptom-based criteria for IBS (Strong recommendation).
  • If diarrhea is prominent with either nocturnal stooling or a history of cholecystectomy, consider testing for bile acid diarrhea (Weak recommendation.
  • Consider anorectal testing or transit studies in the setting of refractory constipation or history suggestive of pelvic floor dysfunction (Weak recommendation).

Management

• Consider relatively low-burden interventions for initial approach to treating IBS symptoms.
  • Consider general lifestyle advice to exercise regularly, drink adequate noncaffeinated fluids, and limit insoluble fiber intake.
  • Recommend intake of soluble fibers and avoidance of insoluble fibers (Strong recommendation).
  • Consider an antispasmodic, using a drug (such as dicyclomine, otilonium, pinaverium, or alverine citrate with simethicone) or peppermint oil (Weak recommendation).
  • For IBS with diarrhea, consider loperamide 4 mg orally initially (then 2 mg after each unformed stool up to 16 mg/day) (Weak recommendation).
  • For IBS with constipation, consider laxatives (Weak recommendation).
  • Consider probiotics (Weak recommendation).
• For persistent IBS symptoms, consider neuromodulators such as low dose amitryptyline (Weak recommendation) and/or self-management support interventions.
• For persistent IBS symptoms with patients motivated for more intensive or expensive treatments:
  • For IBS patients without constipation (with or without diarrhea) particularly for those with potential small bowel bacterial overgrowth, consider rifaximin 400-500 mg orally 2-3 times daily for 10-14 days (Weak recommendation).
  • For IBS with diarrhea, consider alosetron (in females), ramosetron (if available), ondansetron, or eluxadoline (Weak recommendation); discontinue therapy in patients who have severe constipation for more than 4 days; contraindicated in patients without gallbladder
  • For IBS with constipation, use secretagogues such as linaclotide or as a second line agent, lubiprostone (Strong recommendation) or 5-HT4 agonists.
  • Consider a trial of specialized elimination diets, such as low in fermentable oligosaccharides, disaccharides, and monosaccharides and polyols (FODMAPs) (Weak recommendation).
  • Psychological interventions such as cognitive behavioral therapy, interpersonal psychotherapy, relaxation training or therapy, or hypnotherapy (Weak recommendation)