The American College of Gastroenterology (ACG) has developed a clinical guideline for diagnosing and managing patients with irritable bowel syndrome (IBS), which was published in the American Journal of Gastroenterology.

The ACG used the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology to develop 25 clinical recommendations that focus on diagnostic testing and therapeutic options for IBS.

“This ACG clinical guideline was written with the goal of identifying, and answering, key diagnostic and clinical questions relevant to the field of IBS,” stated the ACG’s guideline committee. “This first-ever IBS clinical guideline used trained GRADE methodologists to analyze the published literature relevant to these 25 key questions to assess the quality of evidence and provide the strength of each recommendation.”


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IBS is characterized by recurrent abdominal pain and disordered defecation. Because many patients with celiac disease also present with abdominal pain, bloating, and altered bowel habits, initial screening is needed to rule out celiac disease, noted the guideline committee.

“It is recommended that patients who fulfill symptom-based criteria for IBS with diarrhea (IBS-D) symptoms be screened for celiac disease, given available evidence supports increased odds of celiac disease among patients with IBS symptoms; the significant potential consequences of missing the diagnosis of celiac disease; the availability of highly effective treatment; and the apparent cost-effectiveness of an early diagnosis.”

One challenge when diagnosing patients with IBS is the absence of biomarkers, as it can be difficult to distinguish IBS-D from inflammatory bowel disease (IBD). Fecal lactoferrin (FL) and fecal calprotectin (fCal) are diagnostically useful tests and may be superior to serologic tests in discriminating IBD from IBS, according to the ACG committee.

“fCal and FL are safe, noninvasive, generally available, and can identify IBD with good accuracy,” the committee stated. “Of the serologic testing available, C-reactive protein (CRP) has the highest utility for distinguishing IBD from IBS.”

A careful clinical history focused on key symptoms of abdominal pain and altered bowel habits in the absence of alarm features, and their duration, as well as a physical examination and minimal diagnostic testing are sufficient to confidently diagnose a patient with IBS, according to the ACG committee.

“Not only is a positive diagnostic strategy noninferior to a diagnosis of exclusion, it can substantially shorten time to appropriate therapy,” the committee stated. “A physician who provides a confident, positive diagnosis of IBS made with minimal investigation is more likely to reduce time to initiation of therapy by engaging patients in shared decision-making.” A positive diagnostic strategy, according to the guideline authors, can also help minimize unnecessary testing and reduce health care costs.

The elimination of dietary fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) has been increasingly used as a treatment strategy for patients with IBS. FODMAPs lead to increased gastrointestinal water secretion and fermentation in the colon. Research has shown that a low FODMAP diet was associated with a significant reduction in global IBS symptoms.

“This guideline committee believes that the complexity of the low FODMAP diet, combined with the potential for nutritional deficiencies, and the time and resources required to provide proper counseling on the 3 phases of the plan, requires the services of a properly trained gastrointestinal dietician,” the group stated. “This, however, is not evidence-based but certainly warrants future study.”

Soluble, viscous, poorly fermentable fiber may be beneficial for patients with IBS, and its apparent lack of significant side effects makes fiber a reasonable first-line therapy for patients with IBS symptoms, according to the guideline committee. “The ability to improve stool viscosity and frequency logically argues for the use of fiber in patients with IBS with constipation (IBS-C), although the evidence base to support this contention is weak,” the committee stated.

Antispasmodics are frequently used for treating patients with IBS. However, limited data are available to support their use in the United States, noted the committee. “The data are decades old and of poor quality,” the group stated. “Side effects are common, particularly in the elderly, although anecdotal data suggest that these agents are relatively safe.”

Peppermint oil may be beneficial for overall symptoms and abdominal pain in patients with IBS and has been well-tolerated in the available trials.

The use of probiotics for IBS has increased during the past decade. “However, interpreting the existing literature is problematic because of small studies, the multiple types and strains of probiotics, the inconsistent benefits on individual symptoms, and the lack of rigorous trials based on US Food and Drug Administration (FDA) endpoints,” stated the guideline committee.

The ACG committee recommends the use of chloride channel activators to treat global IBS-C symptoms, noting that lubiprostone 8 mg twice daily “seems effective for relieving global and individual symptoms in patients with IBS-C.”

The guideline committee also recommends the use of guanylate cyclase activators to treat patients with global IBS-C symptoms, and once-daily linaclotide (290 mg) and plecanatide (3 mg) “seem effective for relieving overall and individual symptoms of IBS-C.”

The ACG committee recommends rifaximin to treat patients with global IBS-D symptoms. Rifaximin is a nonabsorbed antibiotic that has been approved by the FDA for the treatment of patients with IBS-D. “Rifaximin is an effective, safe treatment choice for patients with IBS-D symptoms,” the committee stated.

Mixed opioid agonists/antagonists can be used to treat patients with global IBS-D symptoms, according to the guideline. “Eluxadoline improves global IBS-D symptoms in men and women,” the committee noted.

Gut-directed psychotherapies (GDPs) may be used to treat some groups of patients with global IBS symptoms, according to the guideline authors. GDPs include relaxation training and cognitive reframing of unhelpful thoughts. “We suggest the use of GDPs in conjunction with other IBS therapies for patients who are emotionally stable but who exhibit cognitive-affective drivers of IBS symptoms,” the committee stated.

The guideline does not recommend the use of fecal transplant for treating patients with global IBS symptoms. “Alterations in the gut microbiome may lead to the development of IBS symptoms in some patients,” stated the committee. “Changing the gut microbiome to improve IBS symptoms through fecal microbiota transplant (FMT) has innate appeal.” However, there is limited evidence to support FMT for the treatment of IBS and it is of very low quality, the group noted.

“We believe that the information provided in this guideline will help guide both practitioners and researchers for years to come,” stated the ACG committee. “However, as this extensive project evolved, we recognized that there are still significant gaps in our knowledge. Future research is needed to better understand the role of the gut microbiome in patients with IBS and to understand the genesis of visceral pain. Identification of biomarkers to predict treatment response is also essential. Large head-to-head trials comparing different therapeutic modalities are also needed to better provide individualized care.”

Disclosures: Some of the authors reported affiliations with pharmaceutical and biotechnology companies. Please see the original reference for a full list of disclosures.

Recommendations from the American College of Gastroenterology for Irritable Bowel Syndrome

Serologic testing should be performed to rule out celiac disease in patients with irritable bowel syndrome (IBS) and diarrhea symptoms (strong recommendation, moderate quality of evidence).
Fecal calprotectin (or fecal lactoferrin) and C-reactive protein should be checked in patients without alarm features and with suspected IBS and diarrhea symptoms to rule out inflammatory bowel disease (IBD) (strong recommendation, moderate quality of evidence for C-reactive protein and fecal calprotectin; strong recommendation, very low quality of evidence for fecal lactoferrin).
Routine stool testing for enteric pathogens is not advised in all patients with IBS (conditional recommendation, low quality of evidence).
Routine colonoscopy is not advised in patients with IBS symptoms younger than 45 years without warning signs (conditional recommendation, low quality of evidence).
A positive diagnostic strategy is suggested vs a diagnostic strategy of exclusion for patients with symptoms of IBS to improve time to initiate appropriate therapy (consensus recommendation, unable to assess using GRADE methodology).
A positive diagnostic strategy is suggested vs a diagnostic strategy of exclusion for patients with symptoms of IBS to improve cost-effectiveness (strong recommendation, high quality of evidence).
Patients should be categorized based on an accurate IBS subtype as it improves patient therapy (consensus recommendation, unable to assess using GRADE methodology).
Testing for food allergies and food sensitivities is not recommended in all patients with IBS unless there are reproducible symptoms concerning for a food allergy (consensus recommendation, unable to assess using GRADE methodology).
Anorectal physiology testing is advised for patients with IBS and symptoms suggestive of a pelvic floor disorder and/or refractory constipation not responsive to standard medical therapy (consensus recommendation, unable to assess using GRADE methodology).
A limited trial of a low FODMAP diet is recommended in patients with IBS to improve global IBS symptoms (conditional recommendation, very low quality of evidence).
Soluble, but not insoluble, fiber should be used to treat global IBS symptoms (strong recommendation, moderate quality of evidence).
Antispasmodics are not recommended for the treatment of global IBS symptoms (conditional recommendation, low quality of evidence).
Peppermint may be used to provide relief of global IBS symptoms (conditional recommendation, low quality of evidence).
Probiotics are not advised for the treatment of global IBS symptoms (conditional recommendation, very low quality of evidence).
Polyethylene glycol products are not recommended to relieve global IBS symptoms in those with IBS with constipation (IBS-C; conditional recommendation; low quality of evidence).
Chloride channel activators are recommended to treat global IBS-C symptoms (strong recommendations, moderate quality of evidence).
Guanylate cyclase activators are recommended to treat global IBS-C symptoms (strong recommendation, high quality of evidence).
Tegaserod may be used to treat IBS-C symptoms in women younger than 65 years with no more than 1 cardiovascular risk factors who have not had an adequate response to treatment with secretagogues (strong/conditional recommendation, low quality of evidence).
Bile acid sequestrants are not recommended to treat global IBS with diarrhea (IBS-D) symptoms (conditional recommendation, very low quality of evidence).
Rifaximin is recommended to treat global IBS-D symptoms (strong recommendation, moderate quality of evidence).
Alosetron may be used to relieve global IBS-D symptoms in women with severe symptoms that have not responded to conventional therapy (conditional recommendation, low quality of evidence).
Mixed opioid agonists/antagonists may be used to treat global IBS-D symptoms (conditional recommendation, moderate quality of evidence).
Tricyclic antidepressants may be used to treat global symptoms of IBS (strong recommendation, moderate quality of evidence).
Gut-directed psychotherapies may be used to treat global IBS symptoms (conditional recommendations, very low quality of evidence).
The use of fecal transplant is not currently recommended for the treatment of global IBS symptoms (strong recommendation, very low quality of evidence).

Reference

Lacy BE, Pimentel M, Brenner DM, et al. ACG clinical guideline: management of irritable bowel syndromeAm J Gastroenterol. Published online December 14, 2020. doi:10.14309/ajg.0000000000001036