Getting to the bottom of Irritable Bowel Syndrome

Irritable bowel syndrome can be both distressing and socially disabling, but good patient care can make it easier for sufferers to cope with this often life-long condition

Irritable bowel syndrome (IBS) is one of the most common, multifactorial, functional gastrointestinal disorders seen in primary care. Affecting 10-20% of the population, it is most commonly seen for the first time in the 20-30 year age group although it is not uncommon to see teenagers or older people presenting for the first time.¹

More prevalent in the female population (2:1 female:male), IBS is characterised by episodes of diarrhoea and/or constipation together with abdominal cramping and bloating, which can be both distressing and socially disabling in its extreme form.

Previously, IBS was considered to be a diagnosis of exclusion, where patients were subjected to embarrassing and often unnecessary investigations to eliminate other gastrointestinal disorders, before a diagnosis of IBS was given on the basis of 'it's not anything else'. This is now seen as neither evidence-based nor cost-effective care.²

The current evidence for good patient care and management is to establish the diagnosis by thorough assessment, identify red flag symptoms that require further referral, provide drug, psychological and lifestyle advice and develop a partnership with the patient, for what for many will be a life-long condition.

PATHOPHYSIOLOGY

The colon is the last five feet of the intestine and serves two functions in the body. Firstly it dehydrates and stores the stool so that, normally, a well-formed soft stool occurs. Secondly rhythmic contractions of the colon move the stool into the rectum, storing it there until it can be evacuated.

Much of the evidence suggests that there is both motor and sensory dysfunction of the gastrointestinal tract in patients with IBS.³ The gut reactivity is often altered and results in changes in gut motility or gut secretion giving symptoms of diarrhoea or constipation. This is in response to a variety of stimuli which may be environmental (such as life stress) or affecting the gut lumen (bacterial, foods, toxins or inflammation).⁴ Drossman4 also suggests that there is hypersensitivity of the gut, resulting in enhanced perception of pain and sensations. Thus the patient will experience exaggerated, painful contractions for prolonged periods of time, while one part of the colon is contracting with no regard for another part or when the contractions are greatly reduced.

ASSESSMENT & DIAGNOSIS

Diagnosing IBS is imprecise as there is no one specific investigation that can be used to give a definitive diagnosis and each patient's array of symptoms may be diverse with different exacerbating factors.

History taking should include abdominal and bowel symptoms plus an assessment of dietary and lifestyle habits. Keeping a diary to identify exacerbating factors and the symptoms they produce is often helpful. It will take several appointments before a diagnosis can be made.

Anyone presenting with a 6-month history of abdominal pain, distension, bloating or a change in bowel habit should be assessed for IBS.¹ However, initial assessment is ultimately aimed at identifying red flag indicators for serious gastroenterological conditions and making the appropriate referral for further investigations. These include unintentional or unexplained weight loss, rectal bleeding, family history of bowel or ovarian cancer, a change in bowel habit, anaemia, abdominal or rectal masses or increased inflammatory markers (box 1).

In the past IBS was classified using the Manning criteria (box 2), however, it was felt that these criteria were not specific enough and the criteria devised by a group of gastroenterologists from the Rome Foundation should be used.⁵

The Rome III criteria recommend that a diagnosis of IBS be made when a patient has abdominal pain or discomfort for at least 3 months in the previous 12 months and the pain or discomfort shows two of the following features:

1 The pain is relieved with defecation

2 Onset of pain is associated with a change in frequency of passing stools (more or less frequent)

3 Onset of pain is associated with a change in form (appearance) of stools (hard, loose, lumpy, more fluid)

It may be appropriate to use the Bristol stool chart (Figure 1) to help patients establish the form of their stools and open questioning should be used to establish specifics of bowel habit.

NICE1 suggests that in addition to the above, to diagnose IBS a further two or more of the following symptoms should also be present:

• a change in the passage of the stool (incomplete emptying, straining or urgency)
• abdominal bloating or distension
• symptoms exacerbated by eating
• mucus in the stool

Other related symptoms might include nausea, backache, bladder symptoms or tiredness, together with the common IBS risk factors of:

• Female under the age of 50 years
• Previous GI infections (IBS symptoms may be present in up to 30% of patients following bacterial gastroenteritis)⁶
• Previous history of sexual or physical abuse.⁷

Stress is often considered to be a risk factor and patients may feel their symptoms correlate to episodes of life stresses, but currently the substantive evidence for this link is weak8 as researchers have been unable to identify the biological mechanism for this; however, it should not be ruled out as a trigger when looking at the management of the condition.¹

Clinical examination should find all observations within the normal ranges and abdominal examination of the patient should reveal no significant findings, although it is not uncommon to have mild right or left lower quadrant tenderness on palpation or active bowel sounds on auscultation.

Investigations should be undertaken in patients who meet the diagnostic criteria:

• ESR and CRP should be normal, if raised this may indicate other inflammatory bowel diseases such as ulcerative colitis or crohn's disease.
• A full blood count should be undertaken to exclude anaemia, which may indicate GI bleeding or again be present in inflammatory bowel diseases.
• Coeliac disease should be excluded by performing Endomysial antibodies (EMA) or Tissue transglutaminase (TTG).

Unless specifically indicated from the history other investigations are not recommended (box 3).¹

MANAGEMENT OVERVIEW

The management of IBS should be a patient-centred partnership between the healthcare professional and the patient. The individual treatment and management plan should be multifaceted and flexible to incorporate the variations of the condition. It should cover pharmacological and non-pharmacological therapies together with dietary and lifestyle measures that are acceptable and achievable to the patient.

It is important to establish early on that there is no cure for IBS, but reassure that it is not dangerous and does not predispose the patient to other bowel conditions or cancer. The healthcare professional's responsibility lies with supporting the patient, providing advice and education, together with pharmacological treatments that may be necessary. Firmly establishing the idea of self-help is fundamental to successful management, empowering the patient to take control of the symptoms by employing strategies to either lessen, or cope with, the effects they are experiencing.

DIETARY ADVICE

Dietary changes can be the key to controlling the symptoms of IBS, but it is important to remember that what works for one person will not necessarily work for another. Using the diary to identify exacerbating foods is valuable as fibre, lactose, fructose, sorbitol and caffeine are known precipitates, but patients should not just cut out individual foods. Lactose intolerance is present in approximately 10% of patients with IBS9 but total avoidance may not lead to complete symptom relief therefore exclusions should only be advised by a dietician with careful monitoring.¹

Traditionally IBS patients were encouraged to adopt a high fibre diet; in reality this may be detrimental. There are two types of dietary fibre, soluble (root vegetables, legumes, fruit, barley and oats) which readily ferment in the colon to produce gases and physiologically active by-products or insoluble fibre (nuts, seeds, potato skins, bran and wholegrain bread) that is metabolically inert, but absorbs water as it moves through the GI tract providing bulk to the stool. Therefore the need to increase or decrease the type of fibre that is being taken in the diet will depend on whether the IBS is more constipation- or diarrhoea-predominant (box 4).

Symptoms of wind or bloating can be helped by employing the following recommendations from the British Dietetics Association:

• Limit fruit to 3 portions per day
• Reduce intake of resistant starches i.e. those that are not completely digested (part baked breads, reheated potato products, processed foods such as pasta dishes, biscuits and cakes)
• Add golden linseed or oats to the diet, or
• Add a live probiotic.

If patients chose to try a probiotic it is recommended the same one is used for at least a month, but if there is no improvement another could be tried as they contain different bacteria.¹

All patients should be encouraged to develop good eating habits (Box 5).

LIFESTYLE ADVICE

Patients with IBS should be encouraged to ensure there is time for relaxation within their day, as relaxation turns off the natural stress responses, hence relaxing the colonic spasms. Relaxation can be in many forms including simple breathing exercises, meditation, yoga or more physical exercise such as running, swimming or walking. Exercise itself is also recommended, so an assessment and discussion around the amount and type of exercise should be had with the patient. NICE1 suggests using the General Practice Physical Activity Questionnaire (GPPAQ) to identify those with low activity levels and offering brief verbal interventions. As with any increase in exercise, this should be undertaken on a gradual basis but the DH suggest a target goal of 30 minutes moderate intensity exercise at least fives times each week.

PHARMACOLOGICAL THERAPIES

Pharmacological treatments should be determined by the current predominant symptom.

Antispasmodics act on gut muscle at cell level to relax them thus improving the symptoms of pain, bloating and bowel habits. There appears to be no difference between antimuscarinics such as mebeverine hydrochloride or smooth muscle relaxants such as alverine citrate.

Antimotility drugs are useful during episodes of acute diarrhoea; loperamide is significantly more effective at reducing diarrhoea and preventing recurrence than co-phenotrope. However, there is limited evidence of loperamide's efficacy in relieving pain and improving longer-term bowel habit.

Stimulant laxatives such as senna can be used to treat episodes of acute constipation as they improve stool consistency and frequency, however in IBS the aim is to keep the bowel function and motility stable - type 4, and as such an osmotic laxative such as polyethylene glycol is more likely to stabilise bowel form and regularity. Lactulose is not recommended.

If laxatives, antispasmodics or antimotility medication are not effective, a low dose tricyclic antidepressant (TCA) can be tried. It is thought the mode of action is purely analgesic, however patients report significant improvement in all symptoms, (although all studies so far have used high doses of TCAs). Selective serotonin reuptake inhibitors (SSRIs) may also be tried if the TCA is ineffective; again, the mode of action is unclear although SSRIs can cause diarrhoea as a side effect so may be more effective in those with IBS-C. It is unknown if the newer selective noradrenaline reuptake inhibitors (SNRIs) have a place in IBS treatment, however much larger scale trials comparing all three types of antidepressants are proposed to establish a firm evidence base.

PSYCHOLOGICAL INTERVENTIONS

Psychological interventions of cognitive behavioural therapy (CBT), hypnotherapy and psychological therapy should be considered either in isolation or in combination with pharmacological treatment. Again, the physiological mechanism for the effectiveness of these methods is vague and the research has its limitations. Although NICE recommends their use, it has been unable to establish firm evidence for which stage they are most effective, so suggests patients who have tried pharmacological treatments for at least a year may benefit from their use.

The symptoms of IBS are themselves stressful, hence the cycle of discomfort and stress is self-maintaining. Gut-focused hypnotherapy for IBS seems to work by lowering the patient's overall anxiety, lowering the perception of pain and discomfort and by directing positive images to the gut, thus interrupting the cycle.

CBT aims to solve problems concerning dysfunctional emotions, behaviours and thoughts through a goal-oriented, systematic process. Its benefit is that it can be individualised and as such a programme pertinent to each individual can be employed focusing on the specific issues that are troublesome for that patient. Drossman and colleagues3 found significant improvements in anxiety levels as well as physical symptoms when CBT was used as therapy for IBS patients.

NOT RECOMMENDED

Often cited as treatments or therapies, the following have no substantive evidence base and as such should not be recommended: aloe vera, acupuncture, reflexology, herbal remedies and prebiotics.

CONCLUSION

IBS is a common condition seen in primary care. Successful treatment is dependent upon thorough and appropriate assessment and investigation identifying red flag symptoms and referring on where necessary. Treatment should be aimed at the current symptoms and may include pharmacological, lifestyle and psychological interventions. o

REFERENCES

1. NICE Clinical guideline 61. Irritable bowel syndrome in adults: Diagnosis and management of irritable bowel syndrome in primary care. NICE 2008.

2. Spiegel BM, DeRosa VP, Gralnek IM, et al. Testing for celiac sprue in irritable bowel syndrome with predominant diarrheoa: a cost-effectiveness analysis. Gastroenterology, 2004;126:1721-32.

3. Kellow JE, Azpiroz F, Delvaux M, et al. Applied principles of neurogastroenterology: physiology/motility sensation. Gastroenterology. 2006;130:1412-1420.

4. Drossman DA, Camilleri M, Mayes FA. AGA technical review on irritable bowel syndrome. Gastroenterology. 2002;123:2108-2131.

5. Drossman D E Rome III: The Functional Gastrointestinal Disorders

Third Edition, Virginia: Degnon Associates, Inc., 2006.

6. Dunlop SP, Jenkins D, Spiller RC. Distinctive clinical, psychological, and histological features of postinfective irritable bowel syndrome. Am J Gastroenterol. 2003;98:1578-83.

7. Drossman DA, Talley NJ, Leserman J, et al. Sexual and physical abuse and gastrointestinal illness. Review and recommendations. Ann Intern Med. 1995;123:782-794.

8. Bennettb EJ, Tennant CC, Piessea C, et al. Level of chronic life stress predicts clinical outcome in irritable bowel syndrome. Gut.1998;43:256-261.

9. Bohmer C.J. and Tuynman H.A. The clinical relevance of lactose malabsorption in irritable bowel syndrome. European Journal of Gastroenterology & Hepatology 1996;8,1013-1016.

10. Hypnotherapy for IBS http://www.inspiredhypnosis.co.uk/hypnotherapy_IBS.htm accessed 30/9/11