Kimberly Orleck, PA, on Diagnosing IBS-C

Kimberly Orleck, ANP-BC, reviews the key points to consider when diagnosing a patient with constipation to determine if the condition is irritable bowel syndrome with predominant constipation.

Kimberly Orleck, ANP-BC, is vice president of Advanced Practice Providers for United Digestive, Atlanta, Georgia.

IBS-C Diagnosis: ACG Guideline–Based Positive Diagnostic Strategy Using Rome IV Criteria (US Outpatient GI Practice)

• Irritable bowel syndrome with constipation (IBS-C), American College of Gastroenterology (ACG), United States: Current ACG guidelines recommend a positive diagnostic strategy rather than diagnosis of exclusion, because it shortens time to diagnosis, accelerates appropriate therapy, and is more cost-effective, with studies showing low diagnostic yield from additional testing in patients without alarming features.

• IBS-C diagnosis, Rome IV criteria: IBS is defined by recurrent abdominal pain (the hallmark symptom) occurring on average ≥1 day per week over the last 3 months, with symptom onset ≥6 months before diagnosis, and associated with ≥2 of the following: relation to bowel movements, change in stool frequency, or change in stool form; IBS-C subtype requires >25% of stools to be hard/lumpy (Bristol 1–2) and <25% loose/watery (Bristol 6–7), recognizing that subtypes may change over time.

• Minimal diagnostic workup and red flags: IBS should not be diagnosed in the presence of alarming features (e.g., unintentional weight loss, GI bleeding, anemia, fever, nocturnal stools, first-degree family history of colon cancer/IBD/celiac disease, or symptom onset after age 50), which warrant further evaluation; in patients <45 years without alarm signs, ACG recommends against routine colonoscopy, with minimal testing including CBC plus TSH and celiac testing in IBS-C.

TRANSCRIPT:

Hi, everybody. I'm Kim Orleck. I'm a physician assistant practicing at Atlanta Gastroenterology Associates, which is a partner practice of United Digestive. Really happy to be here today to talk about how do we diagnose IBS, particularly focusing on IBS-C. So the first thing I really want to talk through is how this has shifted over time. And now all the guidelines recommend a positive diagnostic strategy versus diagnosing IBS as a diagnosis of exclusion. When we look at the ACG guidelines, again, we recommend this positive diagnostic strategy compared to a diagnostic exclusion strategy due to the fact that this recommendation will improve a time to get patient a diagnosis, improve the time to get them an appropriate therapy, as well as this is more cost-effective strategy. Additionally, when we look at data from studies, we see a low diagnostic yield when additional diagnostic studies are performed in patients with IBS symptoms who don't have any alarming features, which we're going to talk more about.

So when it comes to using this positive diagnostic strategy, what does this mean? The first part we want to think about is using the ROME criteria, the most recent version of which is ROME 4. This is really what's going to help us with our system-based diagnosis. When we look at that ROME criteria, patients have recurrent abdominal pain. We want to remember that abdominal pain is that hallmark symptom of IBS and what often differentiates from other conditions like chronic idiopathic constipation. In addition to just having abdominal pain, when we look at the criteria, they have this pain on average at least 1 day per week, and it's been present for the last 3 months, and it had an onset of at least 6months prior to diagnosis.

Additionally, the pain is associated with at least 2 of the following. The pain is related to bowel movements. It either gets better or worse related to prior or after defecation. It is related to a change in stool frequency or a change in stool form.

Now, when we think about the next step, it's really important that the ACG focuses on categorizing patients based on an accurate IBS subtype, as we know this improves patient therapy. But don't forget that patient subtypes can change over time, meaning they might start with a diagnosis of IBS-C and shift more to IBS-D. When we think specifically of diagnosing patients with IBS-C who again have that abdominal pain occurring at least 1 day a week that started at least 6 months prior to diagnosis and has been present for the last 3 weeks, we want to remember when it comes to the C subtype, it means that more than 25% of their stools are harder lumpy or a Bristol stool frequency type of 1 or 2.

Now, remember that even though a patient is diagnosed with IBS-C, it doesn't mean that they can't have any diarrhea or loose stools. But what we see in this subtype is less than 25% of their stools are loose or watery or Bristol stool 6 or 7. So again, to fit in that IBS-C subtype, more than 25% are the constipation type, whether it's the patient's description or that Bristol Stool Scale, and less than 25% are the diarrhea loose watery or a Bristol stool 60 or 7. So number 1 for this positive diagnostic strategy, it's what I just summarized as their symptoms fitting the ROME criteria. The second part is making sure that these patients don't have any alarming or red flag symptoms. Remember, IBS is not diagnosed if these alarming symptoms are present because then we want to think about another condition and we do want to do a further workup.

When we think about these red flags or alarming symptoms, this includes things like unintentional weight loss, blood in the stool, anemia, fever, nocturnal stools, an alarming family history like a first degree relative with colon cancer, IBD or celiac disease, or new symptom onset after the age of 50. Again, if any of these symptoms exist, further testing is required. The third thing we want to think about, particularly when it comes to IBS-C, is really this minimal diagnostic workup. This really ties back to the red flags. I mentioned a patient is not anemic, so we need to at minimum do a CBC to ensure that there is no anemia. In my clinical practice, I also consider checking thyroid studies like a TSH if that has not been done as a possible cause for constipation. And I also think about celiac disease. While more patients have diarrhea, patients can present with constipation with celiac disease.

I do want to point out here that the ACG guidelines recommend against a routine colonoscopy in patients who have symptoms consistent with IBS who are younger than 45 and have no warning, signs or alarming signs. In summary, when we think about the current evidence in the absence of alarming features, there is no justification for routine colonoscopy in patients with symptoms consistent with IBS younger than 45. When we do look at some studies, we actually see lower rates of polyps in IBS patients compared to non-IBS patients. While we're focusing here on IBS-C, I do want to add that if you're thinking about a patient with IBS-D or even IBS-M who has a diarrhea component, you might want to think about additional testing per the guidelines, those still a minimal diagnostic workup. But in this case, in addition to the CBC, we certainly do want to check celiac serology.

We also want to check our inflammatory markers, including a CRP and a calprotectin to make sure that we are not missing inflammatory bowel disease. Thank you so much for joining today. Hopefully you got some great tips in how to diagnose IBS in accordance with updated guidelines.