Diagnosis and treatment of diarrhea-predominant irritable bowel syndrome

Figures & data

Table 1 Diagnostic criteria for IBS*

IBS (any subtype)	IBS-D	IBS-C	IBS-M	IBS-U
Recurrent abdominal pain or discomfort** ≥3 days/month in the preceding 3 months	Loose or watery stool*** ≥25% of bowel movements	Hard or lumpy stool§ ≥25% of bowel movements	Hard or lumpy stool§ ≥25% of bowel movements	Insufficient alteration of stool consistency to be classified as one of the other subtypes
Must be associated with ≥2 of the following: • Symptom improvement with defecation • Symptom onset with altered frequency of stool • Onset of symptoms associated with altered stool form	Hard or lumpy stool§ <25% of bowel movements	Loose or watery stool*** <25% of bowel movements	Loose or watery stool*** ≥25% of bowel movements

Notes:

* Rome III criteria. Criteria should be met for the previous 3 months, with onset of symptoms ≥6 months before diagnosis;

** uncomfortable sensation that is not described as pain;

*** Bristol Stool Form Score 6–7;

§ Bristol Stool Form Score 1–2. Data from Longstreth et al.⁶

Abbreviations: IBS, irritable bowel syndrome; IBS-C, constipation-predominant IBS; IBS-D, diarrhea-predominant IBS; IBS-M, mixed-symptom IBS; IBS-U, unclassified IBS.

Table 2 Differential diagnosis in patients presenting with symptoms of IBS and alarm symptoms/warning signs

Alarm symptoms/warning signs	Potential differential diagnosis
Anemia	Celiac disease, colon cancer
Family history of colorectal cancer, inflammatory bowel disease, or celiac disease	Celiac disease, IBD, colon cancer
Nocturnal diarrhea that awakens the patient	Colorectal cancer, IBD, microscopic colitis
Onset >50 years of age	Microscopic colitis, colon cancer
Recent antibiotic use	Clostridium difficile colitis
Rectal bleeding	IBD, colon cancer, hemorrhoids, ischemic colitis
Unintentional weight loss (>10% of body weight)	Ischemic colitis, IBD, celiac disease, colon cancer
Persistent frequent diarrhea without hematochezia	Bile acid malabsorption
Persistent bloating and diarrhea unresponsive to dietary interventions	Small intestinal bacterial overgrowth

Note: Data from Wilkins et al.³⁶

Abbreviations: IBD, inflammatory bowel disease; IBS, irritable bowel syndrome.

Figure 1 Symptom improvement with loperamide.

Notes: Patients with IBS-D (N=25) received loperamide 2 mg/day for 1 week, followed by a 4-week dose titration period in which patients could increase the dose by 2 mg/day each week until the response was satisfactory (maximum dose, 8 mg/day). The treatment period was 13 weeks. Data are accumulated mean scores ascertained at 5, 9, and 13 weeks of treatment. ^*P<0.05 vs placebo. Data from Lavö et al.⁴⁹
Abbreviation: IBS-D, diarrhea-predominant irritable bowel syndrome.

Figure 2 Reduction of IBS symptoms with Bifidobacterium infantis capsule administered once daily vs placebo.

Notes: Females with IBS-D recruited from primary care centers were randomized to receive B. infantis 35624 1×10⁸ (n=49) or placebo (n=56) once daily for 4 weeks. Data are least-squares mean changes from baseline at week 4. ^*P<0.03 vs placebo. Data from Whorwell et al.⁵⁴
Abbreviations: IBS, irritable bowel syndrome; IBS-D, diarrhea-predominant IBS.

Figure 3 Percentage of patients reporting GI symptoms.

Notes: (A) Specific foods or food-related mediators often associated with GI symptoms. (B–E) Efficacy of a 4-week very low-carbohydrate (maximum, 20 g/day) diet in patients with IBS-D (n=17). Data from Böhn et al and Austin et al.^55,60
Abbreviations: BSFS, Bristol Stool Form Scale; GI, gastrointestinal; IAC, incompletely absorbed carbohydrates; IBS-D, diarrhea-predominant irritable bowel syndrome.

Figure 4 Efficacy of alosetron in females with severe IBS-D.

Notes: Females with predominantly IBS-D vs other subtypes were randomized to receive either placebo (n=323) or alosetron 1 mg twice daily (n=324) for 12 weeks and were followed for an additional 4 weeks. Adequate relief of pain was ascertained weekly by patient response (yes/no) to the following question: “In the past seven days, have you had adequate relief of your irritable bowel syndrome pain and discomfort?” ^*P<0.05 vs placebo. Reprinted from The Lancet, 355(9209), Camilleri M, Northcutt AR, Kong S, Dukes GE, McSorley D, Mangel AW, Efficacy and safety of alosetron in women with irritable bowel syndrome: a randomised, placebo-controlled trial, 1035–1040., Copyright (2000), with permission from Elsevier.⁶²
Abbreviations: IBS, irritable bowel syndrome; IBS-D, diarrhea-predominant IBS.

Figure 5 Efficacy of rifaximin for patients with IBS-D.

Notes: Patients were randomized to receive placebo (n=635) or rifaximin 550 mg three times daily (n=625) for 2 weeks followed by a 10-week follow-up period. Adequate relief of symptoms was assessed weekly by patient response (yes/no) to the following question: “In regard to all of your symptoms of IBS, as compared with the way you felt before you started the study medication, have you, in the past 7 days, had adequate relief of your IBS symptoms?” From The New England Journal of Medicine, Pimentel M, Lembo A, Chey WD, et al, Rifaximin therapy for patients with irritable bowel syndrome without constipation, 364(1), 22–32. Copyright © (2011) Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society.⁷⁶
Abbreviation: IBS, irritable bowel syndrome.

Figure 6 Diagnostic and treatment algorithm for IBS-D.

Abbreviations: ACG, American College of Gastroenterology; IBS, irritable bowel syndrome; IBS-C, constipation-predominant IBS; IBS-D, diarrhea-predominant IBS; IBS-M, mixed-symptom IBS; IBS-U, unclassified IBS.

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