Diagnostic criteria for the irritable
Johann Hammer a and Nicholas J. Talley bA, Australia
- The Rome criteria for IBS
- Are the Rome criteria valid?
- Studies comparing gastrointestinal symptoms in IBS and organic diseases
- Studies using factor analysis
- Overview of the Rome diagnostic criteria
- Abdominal pain or discomfort plus altered defecation
- Abdominal pain or discomfort relieved by defecation
- Abdominal pain associated with a change in the frequency or consistency of stool
- Altered stool frequency
- Altered stool form
- Altered stool passage
- Passage of mucus
- Bloating and visible distension
- Criticisms of the Rome criteria
- Can the Rome criteria be simplified?
- References and Notes
The Rome criteria represent a consensus viewpoint based on currently available data, but their development certainly does not establish that the content is truly indicative of a specific disease process. There is a limit to the repertoire of gastrointestinal symptoms; because of the low specificity of symptoms, it is understandable that symptoms alone are unlikely to be accurate enough. However, in the absence of a reproducible and accepted biological marker, symptoms currently remain the primary means of identifying and recruiting patients for research. All diagnostic criteria will continue to be controversial until the pathophysiology of irritable bowel syndrome (IBS) is better understood and treatment more appropriately targeted to relevant disturbances. The aim of this review is to present the current Rome criteria and critically evaluate the arguments for and against the individual components being included as part of the criteria.
There have been three Rome working team reports on diagnostic criteria for the irritable bowel syndrome (IBS). The first report in 1988 1 was subsequently modified when a second Rome working team proposed a classification for all of the functional gastrointestinal disorders. 2 A further update of the Rome definition was published in 1992. 3,3a 3,3a Another consensus conference took place in Rome in June 1998 with the aim to refine the current diagnostic criteria. These were published only recently. The aim of this review is to present the original Rome criteria and critically evaluate the arguments for and against the individual components being included as part of the criteria.
The Rome criteria for IBS
The Rome criteria 3,3a 3,3a are summarized in an accompanying article. The Rome I criteria (1992) recommend the diagnosis of IBS only in the presence of the main diagnostic criteria, that is, abdominal pain or discomfort associated with chronic altered bowel habit and two or more of the supportive criteria. In contrast, the Rome II working team (1998) recommends that the diagnosis of IBS be based on the presence of two of the three main diagnostic criteria alone. The supportive criteria may then be used to further classify IBS into diarrhea-predominant or constipation-predominant.
The Rome Criteria for Irritable Bowel Syndrome:
- Abdominal Pain/Discomfort Relieved by Defecation
- Abdominal Pain/Discomfort Associated with Change in Stool Frequency
- Abdominal Pain/Discomfort Associated with Change in Stool Consistency
- Altered Stool Frequency; Altered Stool Form; Altered Stool Passage; Passage of Mucus;
- Bloating or Feeling of Distension
The Manning Criteria for Irritable Bowel Syndrome:
- Pain relieved by defecation
- Looser stools at onset of pain
- More frequent bowel movements at onset of pain
- Abdominal distension (visible)
- Mucus per rectum
- Feeling of incomplete rectal emptying
Are the Rome criteria valid?
Validity refers to the property that diagnostic criteria measure what they purport to measure. Two different research approaches have been taken to validate gastrointestinal symptoms in IBS. One set of studies has evaluated the discriminatory value of gastrointestinal symptoms in IBS versus health and organic disease. These studies compared gastrointestinal symptoms in patients identified as having IBS with patients who were diagnosed to have organic gastrointestinal diseases ( Table 1 ). Although none of the available studies measured the validity of the Rome criteria, all used the gastrointestinal symptoms either described by Manning et al 4 or Kruis et al 5 on which the Rome criteria are based. Another set of studies have attempted to establish whether gastrointestinal symptoms constitute a true ''syndrome of IBS''; they have applied factor analysis, a statistical method used to determine whether there are symptoms that distinctly group together in the population and are consistent with the Rome criteria
Table 1. Results of Studies Comparing Gastrointestinal Symptoms in Irritable Bowel Syndrome (IBS) and Organic Diseases
Study Rome Criteria (%)
Manning et 1978 4
Abdominal Pain/Discomfort Relieved by Defecation Abdominal Pain/Discomfort Associated with Change in Stool Frequency Abdominal Pain/Discomfort Associated with Change in Stool Consistency Altered Stool Frequency Altered Stool Form Altered Stool Passage Passage of Mucus Bloating or Feeling of Distension IBS 81 81 81 59 47 53 Organic 30 30 27 33 21 21
No study has attempted to determine whether the Rome criteria are of value in discriminating IBS from organic disease. Indeed, the literature on the discriminatory value of gastrointestinal symptoms in organic colonic disease is very limited. The available literature suggests that the Manning criteria can discriminate IBS from health or upper gastrointestinal tract conditions but does not provide convincing evidence that the criteria can discriminate IBS from organic disease of the colon. This should not be interpreted to mean that the symptoms comprising the criteria for IBS are invalid; rather, it suggests that they are not specific for IBS.
Overview of the Rome diagnostic criteria
Abdominal pain or discomfort plus altered defecation
The current Rome criteria require that abdominal pain and disturbed defecation must both be present for the diagnosis to be made. 3 This differs from an earlier version of the Rome criteria, which allowed bowel disturbance without pain to constitute IBS. 1 The change represents a conservative approach, as there is currently widespread agreement that abdominal pain is a sine qua non of IBS. The change also reflects the view of the Rome Committee that patients with functional diarrhea and functional constipation (where IBS criteria are not fulfilled) represent distinct conditions, a viewpoint that itself is controversial. The current Rome criteria do not give a specific definition of abdominal pain or discomfort, and thus the criteria may be subject to personal interpretation.
Abdominal pain or discomfort relieved by defecation
This symptom represents one of the key items identified by Manning et al. 4 They showed that 81% of IBS patients had pain relief by defecation compared with only 30% with organic disease. Subsequent studies have consistently shown that pain relieved by defecation occurs less frequently in IBS but was significantly associated with the syndrome.      However, any colonic pain may be relieved by defecation. Indeed, in inflammatory bowel disease this occurs as frequently as it does in IBS. 11
Abdominal pain associated with a change in the frequency or consistency of stool
A change in stool frequency or consistency, or both, represents separate diagnostic criteria in the current Rome classification. Manning et al 4 showed that looser stools at pain onset and more frequent stools at pain onset were both strongly associated with IBS, and this has been confirmed by other clinical and factor analysis studies.          However, the Rome criteria do not only specify a diarrhea-predominant change but also include a constipation type change (i.e., less frequent or harder stools). Heaton et al have identified that changes in stool form, reflecting both slow and fast mouth-to-caecum transit times, have a link to IBS. 22 Certainly, there is a strong clinical impression that when patients report erratic bowel habit, they frequently are experiencing looser or more frequent stools initially, which is then followed by a period with no bowel movements or harder stools. However, the diagnostic value of a constipation type change is unclear, as the studies that have evaluated this change have failed to identify the symptoms as having any clear discriminatory value. 19,23 19,23 It could therefore be argued that the Rome criteria should be modified accordingly.
Altered stool frequency
An increase or decrease in stool frequency is one of the Rome criteria. The definition of altered frequency for research purposes was based on the 95% confidence limits around normal stool frequency reported in the general population. 24 As less than 5% of people have more than three bowel movements a day or less than three bowel movements a week, this was considered a suitable research criterion cut-off. As no better definition has been offered from research studies to date, this seems reasonable. However, changes in stool frequency do not discriminate between IBS and inflammatory bowel disease. 11
Altered stool form
Loose or watery stools, or lumpy or hard stools, do occur in patients with IBS and may be reported to occur alternately. Observable changes in stool form have been linked to IBS. 22 There is a correlation of stool form and mouth-to-anus transit time, 25 as well as colonic transit time. 26 Looser stools were also identified in one study to add additional discriminatory power to the original six Manning symptom criteria. 6
Altered stool passage
Straining, urgency, or feelings of incomplete evacuation are included as one of the Rome criteria. Feelings of incomplete rectal emptying have been confirmed to occur more frequently in IBS than in organic disease. 11 Urgency frequently accompanies other diarrhea type symptoms in IBS and for this reason was included. However, both urgency and straining remain more controversial inclusions, as these symptoms have not been identified to be of discriminatory value to date.
Passage of mucus
Mucus per rectum may be an underestimated symptom in clinical practice. If patients are specifically asked, up to 60% with IBS will report this occurring. 8,11 8,11 This symptom has been shown to be of discriminatory value in IBS versus organic disease but probably does not discriminate from colonic diseases, such as inflammatory bowel disease. 11
Bloating and visible distension
In the original study by Manning et al, 4 visible abdominal distension was an indicator of IBS, but bloating alone was not. Abdominal distension was also more common in IBS patients when compared with inflammatory bowel disease. 11 The Rome criteria broadened this approach based on the clinical impression that bloating is a frequent symptom that accompanies other IBS complaints. The discriminant value of bloating without visible distension is, however, uncertain.
In addition to continuing uncertainty about the value of the individual symptom items, a number of potential criticisms of the current criteria need to be considered. First, there has been some confusion regarding which of the Rome criteria should be applied. In particular, the change to requiring abdominal pain be present remains controversial; whether IBS can exist in the absence of abdominal pain is unsettled. However, the current criteria are conservative. This is consistent with one of the major goals of the Rome criteria, which is to reduce patient heterogeneity in order to enhance the prospects for identifying relevant pathophysiologic disturbances and efficacious therapies.
The Rome criteria do impose constraints including the percentage of time that a symptom needs to be experienced to be considered as diagnostic. Although these are arbitrary, the limits were chosen to reflect those individuals who were at least two standard deviations above the normal mean. This again represents a conservative approach; more appropriate cut-offs may become apparent as further knowledge of the epidemiology and natural history of IBS accumulates.
The criteria could also be criticized because they are not all inclusive and other primary diagnostic symptoms might be considered. For example, it has been suggested that postprandial pain or postprandial urgency or diarrhea are symptoms that should be included as part of the definition based on clinical impressions. Lower abdominal tenderness and lower abdominal bloating is also often seen in clinical practice in patients with IBS. The value of changing the criteria accordingly will depend on data accumulating that this is appropriate, but factor analysis studies do not in general support these additional symptom items.        
The time frame defined as at least 3 months of continual or recurrent symptoms is arbitrary and may be confusing. For example, one could interpret the time frame to mean either a temporally contiguous period of symptoms lasting at least 3 months or a total, but not necessarily contiguous, period of 3 months. Definitions of continual or recurrent have not been provided by the Rome Committees, and if inappropriately interpreted, this may lead to noncomparable patients being enrolled in clinical studies.
It is also unknown whether the Rome criteria have the same diagnostic value in men as in women. 27 The diagnostic value of the Manning criteria, for example, has been shown in one study to be of no value in men, 28 and women were twice as likely to fulfill the Rome criteria 29 or the Manning criteria 30 in random population samples. Talley et al 6 noted that the Manning criteria were most useful in young women. In contrast, Poynard et al 7 did not observe any difference in the sensitivity and specificity of the Manning criteria in men and women. In a study of 156 patients with IBS, 31 mucus, feeling of incomplete evacuation, abdominal distension, and scybala were reported significantly more frequently by women than by men with IBS, although pain relieved by defecation and pain associated with a change in stool frequency and stool consistency were similar in both sexes. 31 Why gastrointestinal symptoms may have different predictive values in men and women remains to be determined. 27
In a recent report of a population-based study in a Swedish municipality, the diagnostic agreement for IBS, defined according to Manning (abdominal pain plus greater than or equal to two of six symptoms in the definition), Rome (modified), and a simple (Swedish) definition (any abdominal pain or discomfort combined with self-reported diarrhea and/or constipation), was analyzed. 32
The overall agreement of the Swedish definition for the identification of IBS compared with the standard IBS definitions was 96% (Rome vs Swedish) and 90% (Manning vs Swedish), respectively. The overall agreement between the Manning criteria and the Rome criteria was 94%. Thus, based on this report, it may be possible to greatly simplify the definition of IBS for epidemiologic studies and in clinical practice.
The Rome criteria represent a consensus viewpoint based on currently available data, but their development certainly does not establish that the content is truly indicative of a specific disease process. The validity of the Rome criteria in discriminating IBS from organic disease has not been determined. There is a limit to the repertoire of gastrointestinal symptoms; because of the low specificity of symptoms, it is understandable that symptoms alone are unlikely to be accurate enough. However, in the absence of a reproducible and accepted biological marker, symptoms currently remain the primary means of identifying and recruiting patients for research. Certainly, the Rome criteria have standardized the field and promoted clinical research. Their development has been welcomed by regulatory agencies and the pharmaceutical industry despite the criticisms that have been engendered. All diagnostic criteria will continue to be controversial until the pathophysiology of IBS is better understood and treatment more appropriately targeted to relevant disturbances.
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