Diagnosis and management of irritable bowel syndrome

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Irritable bowel syndrome or IBS is a very common condition that causes symptoms for about 3.5% of Australians, mostly in younger adulthood or middle age. There's no one cause of the abdominal pain and change in bowel habit that's seen in IBS, and it's currently best described as a disorder of gut–brain interaction.

I'm Dr Laura Beaton, your host for this episode, and I know firsthand as a GP that it actually can be a real challenge to relay this understanding of IBS sensitively and not dismissing any symptoms. So to get us all up to speed on the current best practice in diagnosing and managing IBS, I'm joined by Professor Nicholas Talley to cover this article that he's written in Australian Prescriber.

Nick probably needs no introduction to anybody who attended medical school in Australia, but for those of our listeners who didn't use his textbook on a daily basis, Nick Talley is a gastroenterologist, a senior staff specialist at John Hunter Hospital, and the head of Medicine and Public Health at the University of Newcastle. Nick, thanks so much to you and to your co-author, Dr Savannah Morrison, for this article, and thanks for joining me today to remind us all that just because we can't see IBS specifically on scopes or histopathology doesn't mean it's not real or able to be effectively managed.

Pleasure to be here. Thank you for having me. And yes, IBS is a real disorder and we're starting to understand the pathogenesis a little bit better and certainly it's an important disorder to manage properly.

And thinking about that pathogenesis or pathophysiology, it has recently been changed from being classified as a functional disorder to one of brain–gut interaction. How do you think that really helps us better communicate what we know about IBS to patients?

Well, we know the gut and the brain talk to each other constantly. There's 2-way communication. And we also know if there's disease at the gut level or potentially disease at the brain level, that can affect the other organ very much. And so that's the current thinking about the pathogenesis. For example, after a gastrointestinal infection, acute gastroenteritis, that can be bacterial, protozoal, or viral, you can develop IBS.

In fact, about 10% of people with IBS develop this after an acute gastroenteritis. This is probably because they get a low-grade inflammation. It turns on the immune system, the brain gets impacted, and the disorder begins. And unfortunately, for a significant proportion of those people, that disorder will persist lifelong.

And do you think talking through both the brain and the gut component is more acceptable to patients, or do you think it's really more from a clinician perspective, it's important that we consider both of these aspects, or do you think it's maybe both?

I think it's really both. I think it's important to explain to patients they have a real disorder that they may well have symptoms outside the gut because of this communication between the gut and the brain. And that's very common. And those symptoms may include fatigue, muscle aches, anxiety, depression, and other symptoms; sleep disorders, for example. So these can all occur because the gut becomes damaged and therefore the brain gets affected. And at least for a number of patients, that's a very helpful explanation and makes the disorder that they're experiencing real and they know it's real.

And look, patients do know it's real. They report a wide range of symptoms. Let's go over the clinical features of IBS and particularly the Rome criteria, which were in fact updated in February this year [Rome V].

So the Rome criteria for IBS are the gold standard diagnostic criteria. They're based on the symptoms that people present with. Basically, for a diagnosis of IBS, you need to have abdominal pain. It should be recurrent and not continuous abdominal pain. It may be called discomfort as well, but pain's very characteristic.

Typically, the pain is occurring frequently, at least 3 days per month, but it may well be much more frequent. It's chronic. They've had symptoms for at least the last 3 months, and their symptoms began at least 6 months ago. And this pain can be crampy or constant. It can be anywhere in the abdomen. It's often after meals, but it's in particular related to defaecation.

In other words, you may well have pain relieved by or aggravated by opening your bowels, or when you get the pain, there's a change in stool frequency, either you've got more stools being passed or less stools being passed, or there's a change in the stool form. The appearance of the stool is now different. It may be looser or harder in terms of its consistency and that is linked to the abdominal pain or discomfort.

There's certainly a lot to cover when you're considering a comprehensive assessment of both altered bowel habits and abdominal pain. And you've gone through many of these features of IBS now. When you're doing a clinical workup in rooms, what are the key features that you particularly find helpful when you're considering, 'Look, this is clearly IBS,' or 'Is this another pathology I think I should be considering and need to exclude?'

Well, I certainly want to look for positive symptoms. A patient with abdominal pain, when you ask them what makes it worse, what makes it better, clearly linked to their bowel habit, that's a very characteristic feature of irritable bowel syndrome. And of course, the change in stool frequency and stool form is also part of the syndrome. In fact, you have to have 2 of the 3 related to defecation and/or associated with a change in stool frequency and/or associated with a change in stool form.

But of course, there are other conditions that can potentially present with those symptoms. So the other way to assess the patient is to ask about red flags, alarm features. For example, the symptoms of IBS usually begin in middle age or in younger years. So if the symptoms have first begun over the age of 50, that's a red flag. That may well be something else. For example, colon cancer comes to mind immediately.

IBS doesn't cause GI [gastrointestinal] bleeding. If there's GI bleeding, that's a red flag. IBS does not cause unintentional weight loss usually. So if there's weight loss, that's another red flag. Symptoms waking the patient from sleep at night, progressive abdominal pain, a family history of other diseases like inflammatory bowel disease, coeliac disease, colon cancer. And of course it's very reasonable to do some screening blood studies and, if they're abnormal, that also potentially is a red flag. So the red flags really help you. The absence of red flags, the presence of positive symptoms that's strongly suggestive of IBS.

Of course, we all remember that we should probably be putting about 90% of our clinical acumen into our really comprehensive history taking. So wonderful to remind ourselves to think about these positive features as well as screening for red flag symptoms. And for those of you who are visual learners, the article has some pretty good summary tables and boxes that you can go to to reference later if you need to.

Can we take a moment to discuss testing, and particularly once we've done a good thorough history and examination, what we might order? But actually I'm quite interested in what not to order for IBS, what has pretty low clinical value, even though it might be offered or marketed?

There's a number of tests that the societies who provide guidelines for diagnosis suggest, but I think you need to apply clinical judgement here. A young person presenting with no red flags, absolutely characteristic IBS symptoms, you can make a provisional diagnosis in the office with no tests, and really you're doing a few tests just to check that there's nothing else going on that might be being missed. And there's really only a few of those that are critically important.

And then there are some other potential tests you can think about if you're worried, if there's something else in the history that triggers you to think further. So what are some of the key tests that you should do in probably everybody? Well, I think everyone deserves a full blood count ruling out infection or anaemia; a C-reactive protein, because if that's elevated, that suggests inflammation or infection, which IBS doesn't cause; iron studies if you feel they're necessary can be helpful; and then coeliac serology. One of the few diseases that can present with classical IBS is coeliac disease.

Coeliac serology is recommended for all IBS patients, particularly if they've got diarrhoea as a major symptom. But even if they've got mixed stool habit or even constipation, it's very reasonable to get coeliac serology. Other tests are available. Certainly if there's any suggestion that they might have been exposed to infection or you're worried about gastroenteritis, then a faecal multiplex would be reasonable to look for infection.

A faecal calprotectin, if you're worried about inflammatory bowel disease, is reasonable. It doesn't have to be in everybody, but it's certainly a reasonable test for excluding inflammatory bowel disease, which sometimes can mimic IBS early on before further manifestations. Other tests are not routine but can be considered. For example, looking for thyroid dysfunction with a thyroid-stimulating hormone measurement is reasonable, but typically if you've got thyroid disease causing gut disease, they usually have very clear other features.

You may want to consider a pelvic ultrasound in a female if you're worried about gynaecological pathology, but that's also not routine. And a colonoscopy's not routine either. It really should be left for when you're worried about other disease or you've got red flag features that suggest you need to investigate further.

And some of the low-value tests that we would want to try to avoid ordering?

People often order other routine tests that have a very low yield like renal function tests. Liver function tests have a low yield in this setting. CT scanning is not routine. It exposes the patient to radiation, potentially can lead to false-positive findings that then get investigated unnecessarily and has a very low yield unless there's a red flag situation when you're concerned about malignancy, for example.

During our workup for IBS, part of our questioning was around consistency of stools and change of bowel habit. And your article really outlines that IBS is actually further sub-classified into different syndromal pictures, particularly those who have predominantly constipation, those who have predominantly diarrhoea or mixed. How helpful do you think that this is, as we're thinking about moving on to managing people, to know what pattern of IBS is this?

I think it is very helpful actually. You're quite right. People subdivide IBS into 3 main subtypes. There are 4, but there's 3 main ones. IBS with constipation as the predominant feature. IBS with diarrhoea as the predominant feature. IBS, which is mixed, in other words, alternating between constipation and diarrhoea, and there's a very small group who you don't classify very easily and they probably are not particularly important to worry about. Because usually, even in that group, you can determine the most likely predominant symptom pattern.

The treatments we prescribe today are influenced by the predominant bowel habit. Constipation management is different to diarrhoea management and mixed management is a little bit more complex. So it is sensible to subdivide as you're planning your next steps in the management of the patient.

Great. And before we move on to those next steps and the next step of our podcast today, I'm actually a little bit interested in changing patterns of IBS over time. I'm a GP. I provide longitudinal care and sometimes I actually wonder how often do I need to reevaluate symptoms in someone who's had a pretty clear diagnosis of IBS in the not-too-distant past. In the natural history of IBS, do we expect that the initial pattern might stay the same for someone's lifetime or is it actually normal for it to fluctuate? And is it really just monitoring for red flags that we're thinking of?

So I think it's fair to say it does certainly change over time in a significant number of IBS patients. So every time you see a patient with IBS who has gut symptoms, it is important to quickly check their current bowel pattern because it may well have switched, for example, from diarrhoea to constipation or vice versa. And the mixed group in particular can also switch either way.

So it really is important to consider the current bowel pattern as you may need to change medical management based on this when the patient re-presents. IBS can also disappear eventually, particularly as people get older. Some people lose the syndrome, it just goes away.

A wonderful, hopeful message to be able to pass to some people that not only can we effectively manage many symptoms, but for some people this will remit. So let's talk about management, and it was really nice to read that really the most important thing is a strong clinical relationship and a patient-centred approach. What do you think this specifically looks like and how important is this in IBS?

I think it's incredibly important to reassure people that you recognise the syndrome, recognise their symptoms are real and also help the patient understand that the management is a shared relationship between the doctor and the patient and really working together is the most effective approach leading to the best outcomes that we can achieve.

There's no drug that cures IBS. So incredibly important to manage expectations to provide the diagnosis, explain what IBS is, explain it's a real disease, explain that it's a benign disorder in the sense it doesn't lead to malignancy. There's no associated mortality. However, it still can be a very significant problem for some people and therefore it can't be dismissed as irrelevant or unimportant, and that we are there as doctors to help provide the best management we can and there's a lot that can be done to improve the quality of life as well as the symptoms.

And certainly when thinking about quality of life, a lot of management of chronic conditions involves lifestyle modifications and of course, adequate sleep, regular exercise, stress reduction, avoiding smoking and alcohol. This is going to be helpful in IBS and of course certainly isn't unique to IBS. However, I will say this is really hard for a lot of people to achieve and it is a core piece of GP work. As a subspecialist, how do you explain to patients the essential nature of what is actually quite general advice?

I tell people about the stress reaction. I talk about the hypothalamic–pituitary axis. We know the stress hormonal response is a real response to having stress and having IBS is stressful. Even if stress is not the cause of the problem, it can certainly aggravate the symptoms. Stress reduces the intestinal barrier that is present, actually makes you more at risk of infection and other things that can occur.

So it's very important to approach reducing the stress response as much as possible and having adequate sleep, regular exercise, relaxation approaches, all of this is incredibly important for stress reduction. And then for IBS diarrhoea, smoking is a risk factor. So I always tell all my patients to stop smoking regardless that this is important there as well. And in terms of alcohol, well, alcohol can induce diarrhoea, although it's not associated with IBS per se.

When we're thinking about treatment of IBS, most people might immediately think about dietary modifications. And I wonder what advice is prudent for a generalist like me to give and when do you think specialist dietetics involvement is needed?

Look, I think diet is incredibly important. This is the number one big change in the management of IBS over the last decade or so. We've moved from not starting with diet or not considering this as incredibly important to realising diet is absolutely critical. 70 or 80% of IBS patients have clear dietary triggers that really are important in their disease, important in their symptom management if we can identify those triggers and remove them.

It's also important to recognise we don't want people to overly restrict diets, because if you take the risk, patients may become obsessed with their dietary approaches and actually take diets that are harmful to them, actually have too restrictive a dietary approach. So there's a bit of a balancing act here and this is where education becomes incredibly important. There are some very common food triggers – coffee, I mentioned alcohol, but although it's not directly related to IBS, can precipitate symptoms in some people. Spicy foods, lactose, sugar products, wheat and gluten.

Fibre products sometimes can aggravate IBS, particularly if they've got diarrhoea. High-fat foods can do this as well. So those common food triggers, if they're recognised to be driving symptoms, can be removed very easily. And so having patients complete a food diary, if they're willing to do this, and reviewing the food diary can be very helpful for managing patients in a very simple but effective manner. So drinking enough fluids, reducing coffee and alcohol, reducing fizzy drinks, eating regular small meals, avoiding high-fat foods, avoiding gas-producing foods.

If you're lactose intolerant, avoiding large doses of lactose, reducing it if they're taking large amounts. All of this can be incredibly helpful and it works in about 30, 40% of patients, just very simple dietary advice like this. However, if symptoms are more significant or simple approaches are failing, then I think it's very reasonable to consider referral to a dietitian.

They provide incredible benefits for IBS patients with low fermentable carbohydrate diets being one of the really go-to approaches for IBS. This is the low-FODMAP diet. And the low-FODMAP diet is really an approach to identify foods that are precipitating symptoms that can then be removed long term. The goal is not to stay on the low-FODMAP diet permanently.

The goal is to use the diet approach to identify those key foods that are really inducing symptoms and remove them permanently. And this can work in 50 to 70% of IBS patients. In other words, over half of patients can get better with this approach with no medications or other therapies.

That's wonderful to be able to report to people, and I understand that a really excellent dietitian will be able to help with this, but there are some resources that clinicians or patients can access directly for this. What do you tend to recommend?

Yeah. Look, I recommend the Monash University FODMAP Diet app. That's because it's based in the science that's available. They were the leaders in developing this approach. That's a go-to beginning.

Given that this is a disorder of gut and brain interaction, it does make sense that we consider psychological therapies alongside lifestyle modifications. Are there specific ones that we could recommend for IBS?

There are, although I tend to use and recommend these if patients are failing diet and pharmacological therapies in most cases. However, there's no doubt that psychological therapies benefit people, at least a significant subset of people with IBS. This includes cognitive behavioural therapy and gut-directed hypnotherapy. These therapies really reduce, in my view, the stress response. That's probably why they work.

And by reducing the stress response, they improve gut function and reduce some of the changes that can occur from the hypothalamic-pituitary axis activation through the hormonal response that occurs then. However, the problem always is access to practitioners delivering this therapy. There are apps available that you can use these days that are effective as well, and there are certainly psychologists who can deliver these therapies, but they are not widely available, and that's one of the limitations of psychological therapy for IBS at the moment.

And so it sounds like if you're a generalist talking through dietary advice and pharmacological treatment might be your first step and then thinking about additional psychological support if needed, which brings us to what we've been tiptoeing up to, which is the pharmacological therapies. Which drugs actually have enough evidence that we can actually recommend them at this time for IBS?

There's a number of drugs that have some good evidence. Unfortunately, we don't have all of the drugs available globally. We have some. And it really depends again on what's the predominant symptom problem that is concerning the patient the most. As I said, I think it's incredibly important to subclassify by bowel habit. That really is absolutely critical.

So for example, if the major problem is IBS with predominant constipation, then adding soluble fibre like psyllium is a very sensible approach. Starting at a low dose and building it up slowly is critical, because if you use a big dose to begin with, people will usually not tolerate the soluble fibre and they'll just stop it, which doesn't help you at all. So that can be very helpful, particularly for constipation predominant in IBS. But for some patients with diarrhoea, they will respond to a low dose of soluble fibre like psyllium, because it actually firms up the bowel motion so they get less diarrhoea in that setting.

So that's certainly one of my first go-to approaches, particularly if constipation is a significant issue. If this doesn't help, my next step is what's called an osmotic laxative like polyethylene glycol. Polyethylene glycol, again, you start at a low dose and build it up slowly. It's very, very good treatment for constipation. Unfortunately, it doesn't help the abdominal pain of IBS, so there's a limitation there.

And if that doesn't work for constipation predominant in IBS, then a stimulant laxative like bisacodyl may be used. There's actually a good randomised trial of bisacodyl from Australia that showed it clearly had a significant benefit for constipation in IBS. If diarrhoea is the problem, I mentioned psyllium as one approach in a low dose. You can certainly try this, although watch out it doesn't make them worse. And if that doesn't work for the patient, then loperamide is a very good drug at slowing down intestinal transit.

It's very safe and you use it differently to acute diarrhoea. So loperamide you prescribe on a regular basis, once or twice a day on a regular basis, because that's the way you're going to try and prevent diarrhoea. That's the goal for IBS diarrhoea, not to stop it after they've already had the diarrhoea, which is too late. That's where I start.

Earlier on, we did mention expectation setting. What do you counsel people about how long we need to try these management strategies for to see a benefit? Which are the ones that people are probably going to be signed up for for life, and then the ones that are stopped if symptoms get better?

Yes. I think it's important to give people drug holidays and not to prescribe things forever. That is certainly not the most appropriate practice, particularly for a disorder that comes and goes to some extent, it fluctuates, can even disappear. I think in terms of dietary approaches, you would probably want to continue those reasonably long term. In terms of using products like soluble fibre, that's probably something you would be happy to continue reasonably long term.

But for laxatives, for example, reasonable after 3 to 6 months to give a drug holiday and see what happens and restart if necessary. This also applies to other drugs you may add on to those therapies for the bowel habit change. For example, antispasmodic drugs that can help reduce abdominal pain in IBS, drugs like peppermint oil products or smooth muscle relaxants like mebeverine or even anticholinergics. But I worry about anticholinergics because they're often not particularly well-tolerated.

And you've also got some backup therapies if those medications I mentioned just a moment ago fail, and the backup therapies are actually to consider using a drug class, the low-dose tricyclic antidepressant drug class. This is an effective medication for IBS. It's particularly helpful for IBS with diarrhoea as tricyclics slow intestinal transit. In low dose, these are not antidepressants; these are drugs for gut problems.

The adverse events are much less common in low dose. I'm talking about 10 to 50 mg of, for example, amitriptyline, but you've still got to be careful in older patients who can get side effects with these drugs. And again, if you prescribe a tricyclic antidepressant, if you prescribe a tricyclic, that would be for probably about 6 months and then you would taper it off and you'd go for a drug holiday.

Thanks very much, Nick, for this discussion today. I am certainly feeling much more up to date on what high-value care in IBS looks like. To close out, I'll encourage our listeners to read the full article, which is available for free on the Australian Prescriber website. And as I flagged, it does contain some very helpful summary tables, and especially if you're someone who's studying for exams.

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The views of the host and the guest on this podcast are their own, and may not represent Australian Prescriber or Therapeutic Guidelines. Nicholas Talley is the Chief Investigator of the Centre of Research Excellence in Transforming Gut Health, which is funded by the National Health and Medical Research Council.

He is the president of the Asia Pacific Association of Medical Journal Editors, and Board Chair of Doctors for the Environment Australia. He is an Emeritus Editor-in-Chief of the Medical Journal of Australia and former board director of the Gastroenterological Society of Australia. Please see the Australian Prescriber article for Nick's full declarations of interest.

A reminder you can claim CPD for Australian Prescriber articles and podcasts by self-reporting through your college or institution. For RACGP members, these are fully accredited — visit our website for details.