Dr Ajeya Shetty (left) and Dr Alastair Forbes explain how new guidance from the BSG should speed up the diagnosis of IBS and reduce unnecessary procedures

Irritable bowel syndrome (IBS), non-ulcer dyspepsia, and functional dysphagia all form part of a broader group of functional gastrointestinal disorders, which result in disordered gastrointestinal function in the absence of known structural pathology.

Together they make up the bulk of referrals to gastroenterology outpatient clinics, accounting for 40–60% of cases seen.1

IBS is the most common functional gastrointestinal disorder and is said to affect at least 20% of all women at some time (and about half this number of men).2,3 However, only half of those affected consult their GP.4

IBS is a chronic condition characterised by abdominal discomfort and disorders of defecation. As there are no specific disease markers, diagnosis is made from the combination of typical symptoms, a normal examination, and the absence of alarm features (e.g. weight loss, rectal bleeding, nocturnal symptoms or anaemia).

Table 1 (below) summarises suggested criteria for the diagnosis of IBS.

Table 1: Criteria for diagnosing irritable bowel syndrome*

Manning criteria:6

Abdominal pain plus >=2 of the following:

  • Pain relieved by defecation
  • Looser stools with onset of pain
  • More frequent stools with onset of pain
  • Abdominal distension
  • Passage of mucus in stools
  • Sensation of incomplete evacuation

Rome I criteria:7

 

At least 3 months of continuous or recurrent symptoms with:

  • Abdominal pain or discomfort relieved with defecation,or associated with a change in stool frequency, or associated with a change in stool consistency;

and

  • Two or more of the following on at least 25% of occasions or days:
  • altered stool frequency
  • altered stool form
  • altered stool passage
  • passage of mucus
  • bloating or distension
Rome II criteria:8
  • At least 12 weeks in the past 12 months affected by abdominal discomfort or pain that has two of the following three features:
  • relieved by defecation
  • associated with a change in frequency of stool
  • associated with a change in consistency of stool

The second group of criteria included in Rome I are now considered supportive rather than mandatory in the diagnosis.

* Adapted from Jones J, Boorman J, Cann P et al. British Society of Gastroenterology guidelines for the management of irritable bowel syndrome. Gut 2000; 47 (Suppl II): ii1-ii19, by kind permission of the BMJ Publishing Group.

BSG guidelines objectives

The British Society of Gastroenterology (BSG) has recently published a series of guidelines for the diagnosis and management of IBS.5

The guidelines were compiled by a multidisciplinary group consisting of seven consultant gastroenterologists, a dietitian, a clinical psychologist, a GP, a surgeon and a psychiatrist, at the request of the chairman of the BSG's Clinical Services Committee.

The guidelines underwent a strict review process within the BSG, and then through the editorial process of Gut, in which they were published.

The prime targets for these guidelines are consultant gastroenterologists, specialist registrars in training and GPs. Their purpose is to identify and inform the key decisions to be made in the management of patients thought to have IBS.

Given the extensive overlap between functional gastrointestinal disorders and IBS, it is thought probable that the recommendations could apply in part to other functional disorders including non-ulcer dyspepsia and non-cardiac chest pain.

Robustness of the evidence

The initial draft document produced by the working party was enhanced by a comprehensive literature search, which involved a review of electronic databases including MEDLINE, PubMed, and EMBASE.

Keywords such as 'functional disease', 'dyspepsia', 'irritable bowel syndrome', 'spastic colon', and 'irritable colon' were used in the search.

Additional information was obtained from references in quoted papers. A total of 2521 relevant papers were identified.

The strength of level of the evidence for recommendations made in the guidelines was identified by one of the following, increasingly conventional grades:

  • *** indicates evidence based on large randomised trials
  • ** indicates evidence based on good evidence from trials, but which is less convincing (e.g. because of small numbers)
  • * indicates evidence based on specialist opinion.

Three of the recommendations were graded ***, eight were graded **, and seven were graded *.

Difficulties in providing guidelines for IBS

Compared with clinical trials undertaken in patients with well-defined disease such as peptic ulceration, clinical trials in IBS have the following shortcomings:

  • The conditions being treated are highly variable, with many possible end-points.
  • There is at least a 40% placebo response, making it difficult to advocate therapies that are, in most cases, only marginally more effective than placebos.9
  • Trials completed before the Manning and Rome criteria were available are difficult to evaluate, as the inclusion criteria are so variable.
  • The many clinical trials of only a few days or weeks are of very limited value in a condition that is chronic, and in some cases life- long. It is recommended that trials of IBS treatment should be a mini-mum of 8–12 weeks in duration.10
  • Because IBS (like other functional disorders) is non-fatal, conventional audit measures such as mortality and survival cannot be used to judge or compare different treatment regimens.

Improving patient care

Although a benign condition, IBS is associated with significant disability and healthcare costs. More than 40% of patients report avoidance of some activities as a consequence of their symptoms. These include missing work, and avoidance of travelling, socialising, sexual intercourse, domestic and leisure pursuits, and eating certain foods.11

It is also important to note that patients with IBS are overrepresented in gynaecology and surgical outpatient clinics, and may be especially prone to undergo procedures such as cholecystectomy or hysterectomy when these are poorly or not at all indicated.

The guidelines therefore advocate making a prompt diagnosis early in the course of the condition. It is considered that this can be a confident positive diagnosis in patients under the age of 45 years who meet the criteria for IBS, so long as there are no alarm symptoms, thus avoiding extensive and inappropriate investigations.

Listening to and addressing the patients' concerns, providing explanation and reassurance are also emphasised as important measures in management, supplemented by more disease-specific forms of therapy.

Promoting best practice

A recent review of costs directly attributable to IBS estimated a cost of £90 per consulting sufferer per year.12 With approximately 240 000 new cases each year in the UK,13 this implies a total cost to the NHS of around £22 million per annum.

The guidelines contain a flow chart (see Figure 1,below) for the evaluation of potential IBS, and highlight the key features steering the clinician towards a more organic diagnosis.

Figure 1: Stages in the evaluation of irritable bowel syndrome*
algorithm
* Reproduced by kind permission of the BMJ Publishing Group from: Jones J, Boorman J, Cann P et al. British Society of Gastroenterology guidelines for the management of irritable bowel syndrome. Gut 2000; 47 (Suppl II): ii1-ii19

The guidelines are freely available on the BSG website (www.bsg.org.uk) and comment is invited.

They will be reviewed at 2–3 year intervals, taking account of feedback from the public and professionals alike, as well as incorporating new scientific evidence as it becomes available.

Further high quality research in this area is needed in order to strengthen the evidence base. Only then will gastroenterologists be able to provide robust answers to the many important clinical questions relating to IBS.

References

  1. Farthing MJG. Irritable bowel, irritable body or irritable brain? Br Med J 1995; 310: 171-5.
  2. Thompson WG, Creed F, Drossman DA et al. Functional bowel disease and functional abdominal pain. Gastroenterol Int 1992; 5: 75-91.
  3. Camilleri M, Choi MG. Review article: irritable bowel syndrome. Aliment Pharmacol Ther 1997; 11: 3-15.
  4. Heaton KW, Ghosh S, Braddon FM. How bad are the symptoms and bowel dysfunction of patients with the irritable bowel syndrome? A prospective, controlled study with emphasis on stool form. Gut 1991; 32: 73-9.
  5. Jones J, Boorman J, Cann P et al. British Society of Gastroenterology guidelines for the management of irritable bowel syndrome. Gut 2000; 47 (Suppl II): ii1-ii19.
  6. Manning AP, Thompson WG, Heaton KW et al. Towards a positive diagnosis of the irritable bowel. Br Med J 1978; 2: 653-4.
  7. Drossman DA, Thompson WG, Talley NJ et al. Identification of sub-groups of functional gastrointestinal disorders. Gastroenterol Int 1990; 3: 159-72.
  8. Thompson WG, Longstreth GF, Drossman DA et al. Functional bowel disorders and functional abdominal pain. Gut 1999; 45: II43-7.
  9. Maxton DG, Morris JA, Whorwell PJ. Ranking of symptoms by patients with the irritable bowel syndrome. Br Med J 1989; 299: 1138.
  10. Talley NJ, Nyren O, Drossman DA et al. The irritable bowel syndrome: towards optimal design of controlled treatment trials. Gastroenterol Int 1993; 6: 189-211.
  11. Corney RH, Stanton R. Physical symptoms severity, psychological and social dysfunction in a series of outpatients with irritable bowel syndrome. J Psychosom Res 1990; 34: 483-91.
  12. Wells NEJ, Hahn BA, Whorwell PJ. Clinical economics review: irritable bowel syndrome. Aliment Pharmacol Ther 1997; 11: 1019-30.
  13. Rodriguez LA, Ruigomez A. Increased risk of irritable bowel syndrome after bacterial gastroenteritis. Br Med J 1999; 318: 565-6.

Guidelines in Practice, March 2001, Volume 4(3)
© 2001 MGP Ltd
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