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Managing irritable bowel syndrome in primary care

24 Jul 2019

Dr Andrew Ong, a consultant at the Department of Gastroenterology & Hepatology, Singapore General Hospital, explains to Roshini Claire Anthony the challenges in diagnosing and treating irritable bowel syndrome (IBS).



Based on the Rome II criteria, the prevalence of IBS in Singapore is estimated at 8.6 percent [Am J Gastroenterol 2004;99:924-931] which is similar to the global prevalence of 7.8 percent. [Gut 2017;66:1075-1082]

Due to its heterogeneity, there are many possible mechanisms behind IBS. Common mechanisms attributed to the condition include altered visceral sensitivity, altered brain perception of symptoms, changes in bowel motility and/or secretory function, microinflammation, gut dysbiosis, impaired mucosal functions, and altered gene expression profiles. However, none of these mechanisms have been conclusively and consistently linked with IBS. There are likely subpopulations within the IBS cohort that present with similar symptoms but have very different pathophysiological mechanisms.

Females have a higher risk of developing IBS than males. IBS also runs in families and is likely a combination of genetic factors as well as social learning. There is a significant overlap of IBS with other functional gastrointestinal (GI) disorders such as functional dyspepsia and functional heartburn, as well as with functional non-GI disorders such as fibromyalgia and chronic pelvic pain. This likely reflects similar pathophysiological mechanisms affecting different parts of the GI tract. Thus, patients with any one of these conditions are also at risk of developing IBS.

Psychiatric comorbidities such as depression and anxiety are also closely associated with IBS, and patients with these mood disorders may also be at risk of developing IBS, and vice-versa.


Diagnosing IBS

IBS is diagnosed based on the patient’s symptoms. Based on the Rome IV criteria, diagnostic criteria for IBS includes recurrent abdominal pain or discomfort for at least 3 days per month in the past 3 months associated with two or more of the following:

i) Improvement with defaecation

ii) Onset associated with a change in the frequency of stool

iii) Onset associated with a change in the form (appearance) of stool

These need to be fulfilled for the past 3 months with symptom onset at least 6 months before diagnosis.


Diagnostic challenges

Some patients may have been told that IBS is a diagnosis of exclusion after undergoing investigations. Although it is true that certain conditions such as inflammatory bowel disease (IBD) that may present similarly need to be excluded, a positive diagnosis of IBS can be made in a patient with classical symptoms, aided by a limited set of investigations.

Some patients may have visited multiple healthcare providers (HCPs) as HCPs who are not familiar with this condition will often perform multiple investigations to exclude other diseases. This may leave the patient confused and they may be less trusting of the HCP diagnosing them with IBS. This can be overcome by making a positive diagnosis early and clearly explaining the rationale of the limited investigations. The HCP should not say that the patient has IBS just because investigations do not reveal a diagnosis of other disorders.


Treating IBS

Treatment of IBS requires a multidisciplinary approach, especially for severe cases. Gastroenterologists, dietitians, and psychologists are the main drivers of the treatment strategies. The first step in treatment will always be education and clear explanation of the mechanisms behind the patient’s symptoms, and this would require time spent with the patient to clarify myths and restore trust. This will also help improve the therapeutic relationship between the patient and the doctor and empower the patient to understand the rationale of the treatment options.

Treatment options must be directed at the predominant symptoms. Dietary therapies such as a low FODMAP diet will be tried on patients with strong dietary triggers, especially in those with predominant diarrhoea and bloating. This requires the aid of a dietitian and can be difficult for patients to do on their own.

For mild symptoms of IBS, it may be possible to use simple pharmacological methods such as probiotics, anti-spasmodics, certain antibiotics, laxatives, or anti-diarrhoeal medications to treat the symptoms. Some of the newer laxatives such as linaclotide may offer additional analgesic effects on the viscera and can thus be useful for patients with IBS.

Proton pump inhibitors – one of the commonest drugs prescribed for this indication – are generally not useful for patients with IBS. If pain is a predominant symptom, early use of neuromodulating drugs such as tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, pregabalin, or gabapentin may be necessary to achieve symptom control. Using these medications requires clear communication with the patient. Beneficial effects may kick in after 4–6 weeks of treatment, while the side effects may predominate in the first few weeks. Patients may sometimes stop using the medications, and as such, the HCP needs to support the patient. Most side effects tend to improve after 1–2 weeks of therapy, and it is thus possible to “ride out” the side effects.

For severe cases, combination therapy may be employed. It is also prudent to engage patients early about the possibility of psychological therapies as adjunct treatment, as psychological therapies can counteract maladaptive cognitive and behavioural processes.

Treatment success depends on the modality used. However, it is difficult to compare treatment options as certain treatments are dependent on the HCP (eg, psychological therapies are highly dependent on the psychologist).


Treatment challenges

The main challenge is the lack of multidisciplinary units around the world to manage IBS. As IBS is not a life-threatening condition, it is often ignored by HCPs and not enough education is given to these providers regarding the condition. Since IBS does not have an objective marker to compare treatment response, we need to frequently measure a patient’s symptom severity and quality of life. This requires time spent with the patient, and as such, is often neglected by busy clinicians.

There are no definitive ways to prevent IBS. As per other GI conditions, a healthy balanced diet, good coping mechanisms for stress, and physical activity can help reduce IBS symptom frequency and severity.

There are no medications that can directly trigger IBS symptoms, but medications that can change bowel habits such as opioids causing constipation or diabetic medications causing diarrhoea can worsen IBS symptoms.

IBS has no longstanding consequences to the body. However, many patients who have struggled with chronic pain develop maladaptive thinking processes and behaviour which may exacerbate their symptom severity. If these are not addressed, it may be difficult to fully address the condition.


Common misconceptions

Some patients may have been told by their doctors that the condition is “all in the mind”. Though psychological factors can contribute to the expression of IBS symptoms, it is unlikely that these factors alone give rise to the symptoms. Patients should not be led to think that their symptoms originate from psychological factors.

Patients may also have been told that IBS symptoms can be cured by pharmacological methods. Firstly, IBS is a chronic condition of which there is no cure. Though mild IBS can be treated with pharmacological methods, more severe cases may need a combination of pharmacological, psychological, and dietary therapies.


Practice guidelines

The Rome criteria is the current guideline used locally as well as internationally for the diagnosis of IBS. Other guidelines include the 2018 American College of Gastroenterology IBS guidelines [Am J Gastroenterol 2018 Jun;113(Suppl 2)] as well as the 2010 Asian Consensus on IBS. [J Gastroenterol Hepatol 2010;25:1189-1205]



In summary, it is important that GPs do not over-investigate patients with suspected IBS and they should be confident of a diagnosis that is supported by limited investigations. There must be a rationale for choice of medications, and psychosocial contributing factors to symptoms should not be neglected. Attempts should be made towards restoring a patient’s quality of life. The use of opiates should be avoided.

Specialists have to work with GPs in managing patients with IBS. GPs are often the first port of call for patients, and thus, having a clear understanding of the diagnostic criteria is important. GPs should not reinforce the notion to patients that IBS is a diagnosis of exclusion or that it is all in the mind.

Many of the mild to moderate cases of IBS can be managed in the community with polyclinics and GPs. Specialists are best suited to manage patients who have severe symptoms or complex psychosocial situations.

Dr Andrew Ong
Dr Andrew Ong
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