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FAQs: Irritable bowel syndrome

Irritable bowel syndrome (IBS)?AFFECTS?10 to 15 per cent

oF the population

and is more common in women. However, it appears that many patients, especially men, do not seek help for their problem, despite suffering symptoms for many years.

It is best to think of the condition as a lifelong problem that runs a course of relapse and remission, similar to asthma

or migraine. Consultation may be precipitated by a variety of factors, such as a deterioration in symptoms or fear of malignant disease.

What causes IBS?

It is now recognised that IBS is a multifactorial disorder involving abnormalities of motility, visceral sensation and central processing. It undoubtedly runs in families, suggesting

a genetic component.1 Dietary and psychological influences are also important, although the role of the latter has probably been overemphasised in the past. A significant number of cases seem to be initiated by a dysenteric illness such as salmonella or campylobacter infection and there is increasing evidence that there may be an inflammatory component to the condition.1

How severe can IBS be?

The symptoms of IBS are well recognised but their severity can be considerably underestimated. For instance, many women equate their abdominal pain to that of childbirth, and in the diarrhoea-predominant form of the condition, faecal incontinence is not uncommon. Patients often complain

that their bloating or distension can be very intrusive, which may seem rather surprising until it is recognised that in some individuals' abdominal girth can increase by as much as 12cm during the course of the day.2

What are the

non-colonic features of IBS?

It is important to recognise the non-colonic features of IBS as they often result in patients fearing that serious disease is being missed. They also can lead to patients being referred to the wrong specialty.

Low backache, thigh pain, urinary symptoms and dyspareunia3 are particular features that lead to patients attending orthopaedic, urological or gynaecological clinics, where the outcome is usually unsatisfactory and often accompanied by inappropriate investigation.4 Patients often find it very reassuring to learn that these features are part of their IBS, even if there is little that can be done to relieve them. It is worth remembering that these non-colonic features, when present, help to substantiate the diagnosis of IBS.

Are there any tests to diagnose IBS?

There are still no tests that aid in the diagnosis of IBS and therefore investigation, rather than being exhaustive, should only be undertaken to rule out a realistic alternative diagnosis. Thus in patients with constipation, particularly if aged <40 years, very little investigation is necessary as there is unlikely to be an alternative explanation for their symptoms.

In those individuals with diarrhoea, inflammatory bowel disease and coeliac disease need to be considered, especially if they are experiencing features such as severe mouth ulceration, uveitis or large joint arthralgia. Fortunately, coeliac disease can now be easily screened for using the endomysial antibody test and the ESR remains a good, but not infallible, screen for inflammatory bowel disease.

Colon cancer needs to be considered in patients over the age of 50 or in younger individuals when there is a family history.

A recent change of bowel habit against a background of previously completely normal function is far more worrisome than a constantly changing bowel habit.

The most important point about investigation is to warn the patient that if the diagnosis of IBS is correct then the result will be normal. It is essential to avoid thinking ‘there is nothing wrong with you; it must be IBS'.

How helpful

are the Rome diagnostic criteria?

The Rome Foundation was established to develop ways

of defining functional gastrointestinal disorders. This process resulted in the Rome diagnostic criteria

for IBS; the latest version is Rome III

(see table 1, above).

These criteria are useful when ensuring homogeneity of patient populations for research purposes, but their clinical application has been limited, with only

20 per cent of GPs aware of them.

One major problem with the Rome II?guidelines was that only 73 per cent of individuals with the disorder were diagnosed,6 and it remains to be seen whether Rome III will improve this.

How is IBS best managed?

Management initially involves explaining all the symptoms and identifying any triggering factors. It is surprising how much a tailored management approach can help patients. The condition is likely to be persistent,

and can be exacerbated by dietary indiscretions, smoking cessation, certain drugs such as anti-inflammatories or antibiotics, and psychological upsets.

Symptoms are often worse around the time of menstruation, and interestingly

the condition often improves during pregnancy only to return after delivery.7

Many patients notice that eating makes their symptoms worse and conclude that they have some form of dietary allergy

or intolerance. True dietary allergy is uncommon but there is no doubt that some patients are intolerant of certain foods.

One of the simplest dietary manipulations to undertake is the total removal of insoluble fibre from the diet, which can have a dramatic effect. It is therefore worth trying three months of strict dietary exclusion of anything containing unrefined cereal such as brown bread, most breakfast cereals, brown biscuits, crispbreads and cereal bars.8 Insoluble fibre has laxative properties,

so its exclusion can occasionally make constipation worse, but this may be offset with a laxative.

Coffee and chocolate can also upset some sufferers and it is worth bearing in mind that it is often foods consumed on a regular basis that can cause problems, even if symptoms are intermittent.

When should laxatives and antidiarrhoeals be used?

Laxatives and antidiarrhoeals

can be used as appropriate depending on the bowel habit subtype. If the bowel habit abnormality is persistent they are best used on a regular basis at the lowest dose possible and there is absolutely no evidence that any of these medications can damage the bowel in any way.

Loperamide is probably the best

choice of antidiarrhoeal and sodium picosulphate, macrogols and bisacodyl can all be used safely as laxatives.

Antispasmodics are divided into the smooth muscle relaxants (for example, mebeverine, alverine, peppermint oil) and antimuscarinics (for example, hyoscine butylbromide, dicycloverine). The patient should choose whichever one suits them best, and they can be rotated if they lose their effect over time.

If an antispasmodic on its own is ineffective it is worth trying a combination of a relaxant acting on smooth muscle with an antimuscarinic.

Antispasmodics help pain but seldom have a significant effect on bowel function and consequently may have to be combined with a laxative or antidiarrhoeal as appropriate. If pain is intermittent, there is no reason why they cannot be used

on an as necessary basis, as this helps

to prevent tachyphylaxis. Hyoscine butylbromide is probably surface-acting and has the advantage that it is poorly absorbed in the gut, thus antimuscarinic side-effects are uncommon with this preparation.

What is the

role of antidepressants?

Antidepressants, especially the tricyclics, can be very helpful but should only be used at a low dose, with 10-20mg of nortriptyline usually being sufficient.

It should be emphasised to the patient that the drug is not being used primarily for its antidepressant activity, and at a low dose is unlikely to cause side-effects.

Should I refer

a patient to secondary care?

Referral to secondary care is usually required when the patient fails to respond to the usual measures, when the diagnosis is in doubt or when further investigation is judged necessary.

In the case of treatment failure, further options are limited except in specialist centres. The most commonly used approaches are exclusion diets and a variety of behavioural therapies. The latter is very much dependent on local availability but the most commonly used

is cognitive behavioural therapy.

Gut-focused hypnotherapy is especially effective9 but is not generally available and it is essential that the hypnotherapist has been trained in the technique.

What red flags should GPs

look out for?

Although cancer of the colon does not appear to be any more common in these individuals, it should be considered if a patient develops any of the usual alarm symptoms, such as rectal bleeding or weight loss. Another useful pointer is if the patient describes a change in their symptoms that they have not previously encountered. Patients with IBS have usually had their problem for many years and become very familiar with the range of symptoms they experience, and their pattern. Thus, if they suddenly report a change from this stereotype it should be viewed as a red flag.

What types of new treatment may be available

in the future?

There is a considerable amount

of research on new therapies focusing on approaches such

as the modulation of serotonin, cholecystokinin and corticotrophin releasing hormone. Probiotics are also

an area of great interest, although unfortunately none of these approaches are likely to be available in the immediate future. For the time being we will have to work with the therapies available, but IBS should by no means be regarded as untreatable.

References

1 Drossman DA, Camilleri M, Mayer EA et al. AGA technical review on irritable bowel syndrome. Gastroenterology 2002;123(6):2108-31

2 Houghton LA, Lea R, Agrawal?A,?et al. Relationship of abdominal bloating to distention in irritable bowel syndrome and effect of bowel habit. Gastroenterology 2006;131(4):1003-10

3 Whorwell PJ, McCallum M, Creed FH, et al.

Non-colonic features of irritable bowel syndrome.

Gut 1986;27(1):37-40

4 Prior A, Whorwell PJ. Gynaecological consultation

in patients with the irritable bowel syndrome. Gut 1989;30(7):996-8

5 Longstreth GF, Thompson WG, Chey WD et al. Functional bowel disorders. Gastroenterology

2006; 130:1480-1491

6 Lea R, Hopkins?V, Hastleton J et al. Diagnostic criteria for IBS: utility and applicability in clinical practice. Digestion 2004;70:210-3

7 Agrawal A, Whorwell PJ. Irritable bowel syndrome: diagnosis and management. BMJ

2006;332(7536):280-3

8 Francis CY, Whorwell PJ. Bran and irritable bowel syndrome: time for reappraisal. Lancet 1994; 344;39-40

9 Gonsalkorale WM, Miller V, Afzal A, et al. Long term benefits of hypnotherapy for irritable bowel syndrome. Gut 2003;52:1623-9

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