What is the evaluation of Irritable Bowel Syndrome (IBS)?

From the Guidelines

The evaluation of Irritable Bowel Syndrome (IBS) should prioritize a thorough clinical assessment, using the NICE guideline definition, over rigid diagnostic criteria like the Rome IV criteria, to ensure that patients with troublesome symptoms receive a clear diagnosis and appropriate management options. According to the British Society of Gastroenterology guidelines on the management of IBS 1, the key to diagnosis starts with skilled, targeted history taking and examination, considering the patient’s medical history and life circumstances. The following steps can be taken to evaluate IBS:

• Start with a detailed patient history and physical examination
• Perform basic blood tests: Complete blood count, C-reactive protein, and celiac serology
• Conduct stool tests: Fecal calprotectin and tests for parasites/ova
• Consider colonoscopy for patients over 50 or those with alarm symptoms (e.g., weight loss, rectal bleeding)
• Classify IBS subtype based on predominant stool pattern, but avoid using overly restrictive diagnostic criteria It's also important to consider the potential co-occurrence of mental health disorders, such as anxiety and depression, which are highly prevalent in patients with IBS 1, and to tailor the management approach to meet the needs of these patients. Additionally, dietary modifications, such as the low-FODMAP diet, can be an effective treatment for IBS symptoms 1. By taking a comprehensive and multidisciplinary approach to evaluating and managing IBS, clinicians can improve patient outcomes and quality of life.

From the FDA Drug Label

The trials examined a composite endpoint which defined responders by IBS-related abdominal pain and stool consistency measures Patients were monthly responders if they met both of the following criteria: • experienced a ≥30% decrease from baseline in abdominal pain for ≥2 weeks during the month following 2 weeks of treatment • had a weekly mean stool consistency score <4 (loose stool) for ≥2 weeks during the month following 2 weeks of treatment The Rome II criteria further categorizes IBS patients into 3 subtypes: diarrhea-predominant IBS (IBS-D), constipation-predominant IBS (IBS-C), or alternating IBS (bowel habits alternating between diarrhea and constipation). **Rome III Criteria: Recurrent abdominal pain or discomfort (uncomfortable sensation not described as pain) at least 3 days/month in last 3 months associated with two or more of the following:

1. Improvement with defecation;
2. Onset associated with a change in frequency of stool;
3. Onset associated with a change in form (appearance) of stool

The evaluation of Irritable Bowel Syndrome (IBS) is based on the following key criteria:

• Abdominal pain: a ≥30% decrease from baseline in abdominal pain for ≥2 weeks during the month following 2 weeks of treatment
• Stool consistency: a weekly mean stool consistency score <4 (loose stool) for ≥2 weeks during the month following 2 weeks of treatment
• Rome II and Rome III criteria: recurrent abdominal pain or discomfort associated with changes in frequency, form, or improvement with defecation 2 2 Main points to consider in the evaluation of IBS:
• Diarrhea-predominant IBS (IBS-D): characterized by loose or watery stools
• Constipation-predominant IBS (IBS-C): characterized by hard or lumpy stools
• Alternating IBS: characterized by alternating bowel habits between diarrhea and constipation It is essential to assess IBS symptoms using a comprehensive approach, including patient history, physical examination, and diagnostic tests to rule out other conditions.

From the Research

Evaluation of Irritable Bowel Syndrome (IBS)

The evaluation of IBS involves a combination of clinical examinations, laboratory investigations, and symptom-based diagnostic criteria.

• The diagnosis of IBS should be made on clinical grounds, using symptom-based criteria such as the Manning or Rome criteria, unless symptoms are thought to be atypical 3.
• A positive diagnosis of IBS can be achieved through application of symptom-based clinical criteria, careful history and physical examination, evaluation for alarm sign/symptoms, and judicious use of diagnostic testing 4.
• The Kruis score, Manning criteria, and Rome IV criteria are commonly used diagnostic criteria for IBS, with the Kruis score outperforming the Manning criterion in distinguishing between organic bowel disease and IBS 5.
• Laboratory tests such as complete blood count (CBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) can be used to support the diagnosis of IBS 5.

Diagnostic Criteria

• The Rome IV criteria are widely used for the diagnosis of IBS, and involve the presence of abdominal pain at least 1 day per week in the last 3 months, associated with the alteration of the intestinal bowel habits 6.
• The Manning criteria and Kruis score are also used for the diagnosis of IBS, with the Kruis score being more effective in distinguishing between organic bowel disease and IBS 5, 3.

Laboratory Investigations

• Laboratory tests such as CBC, ESR, and CRP can be used to support the diagnosis of IBS, but exhaustive investigation has a low yield 5, 7.
• Excluding celiac disease in all patients consulting with symptoms suggestive of IBS is worthwhile, but evidence for performing other investigations to exclude organic disease is not convincing 3, 7.