Dr Lisa Das MBBS Board Certified in Gastroenterology (ABIM) is a Consultant Gastroenterologist at Bart’s and the London NHS Trust Bupa Cromwell Hospital.
Irritable bowel syndrome (IBS) is a complex disorder that is associated with altered gastrointestinal motility, secretion and sensation. IBS has a significant impact on quality of life and healthcare utilisation, and it remains a clinical challenge evenin 2015. It is the most commonly diagnosed gastrointestinal condition, and the most common reason for referral to our clinics. The prevalences worldwide, and it may affect up to one in five people at some point in their lives.
Why is this disorder so challenging when many describe it as ‘just IBS’?The conundrum lies in the many manifestations of IBS, and the fact that it cannot be confirmed by aspecific test or structural abnormality. Gastroenterologists diagnose IBSclinically using criteria based on the patient’s history and symptoms, according to the current gold standard of the Rome III criteria*.There is no clinical evidence to recommend the use of biomarkers in blood to diagnose IBS. Various mechanisms and theories have been proposed about its aetiology, but the biopsychosocial model is the most accepted.
There is no single definitive treatmentfor IBS, so traditional management has been symptom based. There have, however, been recent developments in the understanding of the complex interaction between the gut, immune system and nervous system, leading to an expanded range of therapeutic options for relief of both bowel movement related symptoms and pain. As ever though, a strong doctor patient relationship remains the key for the management of realistic expectations and effective treatment of patients.
Recent guidelines from AGA(American Gastroenterological Association) emphasise that IBS is no longer a diagnosis of exclusion. Instead clinicians are encouraged to make a positive diagnosis using the Rome III Criteria alone. To this end the definition of IBS has been simplified to that of the typical manifestations being discomfort or abdominal pain relieved by defecation, associated with a change in stool form.
Patients with IBS can present with a variety of symptoms which include both GI and extra intestinal complaints. Factors such as emotional stress and eating may exacerbate pain. In contrast, defecation usually provides some relief. Patients with IBS complain of altered bowel habits, ranging from diarrhoea (IBS-D),constipation (IBS-C), or alternating diarrhoea and constipation (IBS-M).
Other red flags noted during the history must not be neglected. Large volume or nocturnal diarrhoea, bloody stools, anaemia or weight loss are not associated with IBS and suggest organic disease requiring further, often urgent investigation.
Patients with IBS-C may experience a sensation of incomplete evacuation, and periods of constipation may last from days to months, alternating with diarrhoea or normal bowel function.
Abdominal bloating or the feeling of abdominal distension are very frequent complaints in IBS and are not represented in the Rome III criteria. They were however highlighted in the 1978 Manning criteria** which preceded the development of the Rome definitions.
Other digestive symptoms such as dysphagia, intermittent dyspepsia, nausea and non-cardiac chest pain are also often associated with IBS. Moreover, extraintestinal symptoms such as psychiatric disorders, especially depression, anxiety and somatoform disorders occur frequently in IBS.
The non GI, non psychiatric disorders with the best documented association with IBS are fibromyalgia, chronic fatigue syndrome, temporal mandibular joint disorder, chronic pelvic pain and headaches. These comorbidities are correlated with enhanced medical seeking behaviours, worse prognosis, and higher rates of anxiety and depression, which all result in a reduced quality of life. The prompt identification of these clinical problems may improve the therapeutic options and prevention strategies in many patients.
The basic diagnosis should include a careful and thorough medical history. Having identified a symptom complex compatible with IBS based upon Rome III criteria, patients with no alarm symptoms or family history of IBD (inflammatory bowel disease) or colorectal cancer may only require a limited number of diagnostic studies to exclude organic disease. A considerable number of patients will not require any tests at all. This limited diagnostic approach excludes organic disease in more than 95% of patients, and it is rare to use abdominal imaging tests for patients with suspected IBS and no alarm features.
IBS has no definitive treatment, but may be controlled by eliminating exacerbating factors such as stress, dietary habits or use of certain drugs. The traditional management of IBS is symptom based, and the fundamental aspect of doctor/patient interaction remains the cornerstone of therapy. The treatment goal is to try to eliminate or decrease the patient’s primary symptoms, which should be addressed on the first consultation.
The intake of foods does not cause IBS, but many IBS patients have nonspecific intolerance to foods. The low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet is now accepted as an effective potential strategy for managing the symptoms of IBS, but limitations still exist due to the fundamental difficulty of placebo control in dietary trials, and the difficulty of maintaining such a diet in a chronic condition.
In general, IBS patients should avoid foods that trigger an onset of their symptoms, consume a minimum of high fat foods and take part in regular physical activity. Regarding other treatment options, Bifidobacteria, Saccharomyces boulardii and other combinations of probiotics demonstrate some efficacy in IBS, and antispasmodics remain a firstline therapy for managing abdominal pain.
Antidepressants have analgesicproperties, and Tri Cyclic Antidepressants and Selective Serotonin Reuptake Inhibitors appear to be more effective than placebo in the overall reduction of symptoms associated with IBS. Dietary modifications and lifestyle should be the initial tools for the treatment of patients with constipation predominant IBS and mild to moderate symptoms.
Because of the abnormalities in bowel habits associated with each IBS subtype, it is not likely that one agent would successfully treat all three subtypes. Some of the newer agents for IBS-C are Lubiprostone (which enhances chloride chloriderich intestinal fluid secretion), Linaclotide (which stimulates intestinal fluid secretion and transit), and Prucalopride (which has been reported to reduce general IBS symptoms, but is only approved for female patients).
Whatever new medications are in the pipeline for IBS, we need to understand the particular concerns and fears of patients and allay these with confidence and reassurance. Knowledge of and consideration of all available treatment options is key once a solid patient physician relationship has been established.
*The Rome III criteria for irritable bowel syndrome (IBS) is as follows:
Symptoms of recurrent abdominal pain or discomfort and a marked change in bowel habit for at least six months, with symptoms experienced on at least three days of at least three months. Two or more of the following must apply:
- Pain is relieved by a bowel movement
- Onset of pain is related to a change in frequency of stool
- Onset of pain is related to a change in the appearance of stool.
**The Manning criteria is a diagnostic algorithm used in the diagnosis of IBS. The criteria are:
Onset of pain linked to more frequent bowel movements:
- Looser stools associated with onset of pain
- Pain relieved by passage of stool
- Noticeable abdominal bloating
- Sensation of incomplete evacuation more than 25% of the time
- Diarrhoea with mucus more than 25% of the time