IBS-D is a gastrointestinal tract disorder characterized by abdominal pain associated with altered bowel habits that occur at least once weekly on average for 3 months or more.
IBS can be further characterized by subtype, and may alternate between IBS subtypes during their lifetime.
Diarrhea-predominant IBS (IBS-D), which is the most common IBS subtype, is reported in 40% of patients with IBS.
Constipation-predominant IBS occurs in 35% of cases and mixed or alternating IBS in 23%.
IBS-D is characterized by abnormal bowel movements, which are predominantly diarrhea (> 25% of bowel movements mushy or watery and < 25% hard lumps or sausage-shaped but lumpy).
Diarrhea-predominant IBS (IBS-D), in which abnormal BMs are mostly diarrhea, or > 25% of BMs with BSS types 6 or 7 and < 25% with BSS types 1 or 2.
Constipation-predominant IBS (IBS-C), in which abnormal bowel movements (BMs) are mostly constipation, or > 25% of BMs with Bristol Stool Scale (BSS) types 1 or 2 and < 25% with BSS types 6 or 7.
Mixed or alternating IBS (IBS-M), in which abnormal BMs usually alternate between diarrhea and constipation, or > 25% of BMs with BSS types 1 or 2 and > 25% with BSS types 6 or 7.
Unclassified IBS (IBS-U), in which patients have a diagnosis of IBS, but bowel habits cannot be categorized using the criteria for IBS-D, IBS-C, or IBS-M.
Postinfectious IBS (PI-IBS) is a consequence of GI tract exposure to bacterial, viral, or parasitic pathogens.
Travelers’ diarrhea significantly increases the odds of developing IBS within 6 months after completing travel to a developing country.
Patients were 4 times more likely to develop IBS 90 days or more after a diagnosis of giardiasis compared with individuals without giardiasis.
In a longitudinal study of a general population sampling that had baseline and 10-year data, 214 (5.5%) of 3873 individuals had IBS at baseline; of these 214 patients, 67.3% reported IBS symptoms after 10 years.
The overall global prevalence of IBS in adults is reportedly 11.2%,5 suggesting that approximately 36 million individuals in the United States may be affected.
Overall, IBS is more prevalent in women than in men (64% vs 36%, respectively)
There may be a greater willingness to seek medical care among women accounting for increased prevalence.
Among although IBS can occur at any age, those affected are typically less than age 50.
The total direct and indirect costs of IBS have been estimated to total $30 billion annually17 and are estimated to be greater than those of other common chronic illnesses, including congestive heart failure, asthma, and migraine.
Factors that contribute to the economic burden of IBS include outpatient care (eg, primary care visits, medication costs) and the negative impact on patient employment status.
At least half of patients report limiting employment and academic and social activities because of IBS.
In an analysis that included 18 studies, days of work missed related to IBS ranged between 8.5 and 21.6 annually.
Patients with IBS may alter their lifestyle by limiting social activity and by remaining homebound
Most IBS patients reported either comorbid physical or psychological disorders associated with decreased quality of life and increased GI symptom severity.
Compared with patients with IBS-C, patients with IBS-D have reported significantly lower quality of life.
Patients with IBS may perceive themselves as stigmatized because of their condition.
IBS is associated with a substantial socioeconomic burden and negatively impacts patient quality of life.
A biomarker test has the potential to aid in the diagnosis of IBS.
Some patients with IBS-D have been shown to have increased concentrations of antibodies against bacterial cytolethal distending toxin B (CdtB) and human vinculin compared with healthy individuals.
Extraintestinal symptoms are reported more frequently by patients with IBS than by patients with GI symptoms unrelated to IBS and include fatigue, sleep disruption and back pain.
Nausea, fibromyalgia, chronic pelvic pain syndromes, and restless legs syndrome are also found as comorbid conditions in patients with IBS.
Some of these conditions also are associated with small intestinal overgrowth.
Patients with IBS indicated that pain, bowel problems, bloating, and dietary limitations contribute most to their disease severity.
The pathophysiology is considered multifactorial, and may include visceral hypersensitivity, fecal microbiota dysbiosis, increased GI tract permeability, altered immune responses, altered GI tract motility, small intestinal bacterial overgrowth, altered gut-brain axis interactions, and food sensitivity.
IBS patients exhibit differences in the quantity and composition of gut microbiota in the large intestine.
IBS is underdiagnosed.
Abdominal pain is a key symptom required for a diagnosis of IBS.
Bloating, abdominal distension, while common or neither of these symptoms is required to establish a diagnosis of IBS.
One goal of IBS-D treatment is to provide adequate symptom relief, which can start with dietary and lifestyle modifications and over-the-counter therapies such as loperamide and probiotics.
If symptoms worsen during probiotic administration, then comorbid SIBO should be considered.
Presently, only 3 pharmacologic agents have received regulatory approval for the treatment of patients with IBS-D in the United States: alosetron, eluxadoline, and rifaximin.
Overall, pharmacologic therapies used concurrently with diet and lifestyle modification and psychologic interventions may benefit patients with
Treatments administered daily in patients with IBS-D include eluxadoline, serotonergic agents, antidepressants, and psychologic interventions
Eluxadoline, an orally administered μ-opioid and κ-opioid receptor agonist and δ-opioid receptor antagonist indicated for the treatment of adults with IBS-D, slows GI tract motility and improve abdominal pain.
Alosetron is indicated for the treatment of women with severe IBS-D with symptoms lasting 6 months or longer that have not responded to conventional therapy.
Comorbid neuropsychiatric conditions such as depressive and anxiety disorders are frequently observed in patients with IBS.
Treatment with antidepressants and selective serotonin-reuptake inhibitors result in a higher percentage of patients experiencing symptom improvement, including abdominal pain.
Rifaximin 550 mg is an oral nonsystemic antibiotic indicated for the treatment of adults with IBS-D and is administered 3 times daily for 2 weeks.
Rifaximin improves symptoms of IBS through its modulation of the gut microbiota and host interactions, including treating SIBO via antimicrobial activity, inhibiting bacterial translocation, and altering inflammatory responses.
Administration of antibiotics is considered a risk factor for the development of Clostridium difficile infection.
After only 10 days of treatment with systemic antibiotics, the gut microbiota can be altered for up to 1 year.
Both the single and the repeat 2-week courses of nonsystemic rifaximin had minimal effects on the gut microbiota of patients with IBS-D.
Repeat treatment with rifaximin does not have a clinically impact on the long-term resistance of stool or skin bacteria to either rifampin or non-rifamycin antibiotics in patients with IBS-D.
Antispasmodic agents improve abdominal pain in patients with IBS by relaxing the smooth muscle of the GI tract, but have received a weak recommendation by the American College of Gastroenterology for short-term symptomatic relief, due to a significantly greater percentage of patients with IBS reported AEs with antispasmodic agents compared with placebo.
Adverse events reported with antispasmodics include: dry mouth, dizziness, and blurred vision.
Loperamide is an over-the-counter, on-demand therapy that is often considered first by patients to help manage IBS-D symptoms.
Probiotics improve symptoms in patients with IBS, but has a weak recommendation for its use because of inconsistencies across studies in formulation and dosing, and in the bacterial species and strains used.
Rifaximin 550 mg is an oral nonsystemic antibiotic indicated for the treatment of adults with IBS-D and is administered 3 times daily for 2 weeks.
Rifaximin is believed to modulate gut microbiota and host interactions, including treating SIBO via antimicrobial activity, inhibiting bacterial translocation, and altering inflammatory responses.
Probiotics are more efficacious than placebo for improving global IBS symptoms, abdominal pain, bloating, and flatulence, however there is inconsistencies across studies in formulation and dosing, and in the bacterial species and strains used.
Probiotic adverse events are more likely to occur with probiotics than placebo.
There is only weak recommendation for the administration of probiotics for IBS,