Toward a new understanding of the functional gastrointestinal disorders

For centuries, physicians and historians have recognized that it is common for maladies to afflict the intestinal tract, producing symptoms of pain, nausea, vomiting, bloating, diarrhea, constipation, difficult passage of food or feces, or any combination.1When these symptoms are experienced as severe, or when they impact on daily life, those afflicted often attribute the symptoms to an illness and seek medical care. Traditionally, the physicians caring for these patients will search for inflammatory, infectious, neoplastic, and other structural abnormalities to make a specific diagnosis and offer specific treatment. Yet as has been common in medical practice,2 when no structural etiology is found, the patient is diagnosed as having “functional” symptoms and is treated symptomatically.

Until recently, the limited scientific knowledge about the pathophysiology of these symptoms, and the need to diagnose by excluding “organic” disease, has led physicians to feel uncertain about the legitimacy of these symptoms as bona fide disorders.3 Some have felt insecure in their ability to manage patients with these conditions, and might even avoid caring for patients with these complaints. But over the past two decades, two important processes have occurred to legitimize these conditions, and to increase attention toward the research and clinical care of patients with functional gastrointestinal disorders (FGID). The first has been a shift in conceptualizing these disorders from a disease-based, reductionistic model, where the effort is directed toward identifying a single underlying biological etiology, to a more integrated, biopsychosocial model of illness.4 ,5 The latter model allows for symptoms to be understood as physiologically multidetermined (e.g., altered motility, enhanced visceral sensitivity, brain–gut dysregulation) and as modifiable by sociocultural and psychosocial influences. The second change has been the remarkable growth in investigative techniques that support this newer conceptualization of brain–gut interactions: improved motility assessment, the development of the barostat, imaging of the brain (positron emission tomography (PET), functional magnetic resonance imaging (fMRI)), standardized psychological diagnostic instruments, and the molecular investigation of brain–gut peptides. As a result, over the past two decades, there has been a 10-fold increment in Medline citations about irritable bowel syndrome (IBS), a much larger number of symposia and presentations at national and international meetings about the FGIDs, and increased effort by pharmaceutical companies to identify and test receptor-active agents to treat these disorders.

These developments built support for an international effort to characterize and classify the FGIDs by investigators and clinicians, pharmaceutical regulatory organizations, pharmaceutical companies, and federal research agencies. The Multinational Working Teams to Develop Diagnostic Criteria for Functional Gastrointestinal Disorders (Rome Committees) began in the mid 1980s as a series of committees that developed consensus criteria for over 20 FGIDs and published them in several documents in Gastroenterology International. These documents were eventually updated and compiled into a book6 as the Rome criteria.

In this supplement, we present the second major effort of the Rome committees: the update of our growing knowledge of the FGIDs over the past five years. We include five articles that detail the FGIDs based on anatomic region, (esophageal, gastroduodenal, bowel, biliary, anorectal), and a separate article on pediatric FGIDs. We also present several articles summarizing current knowledge on the physiologic (motility/sensation), basic science (brain–gut), and psychosocial aspects of the FGIDs, and provide recommendations for the design of treatment trials for these disorders. In addition, we include the revised (Rome II) diagnostic criteria for the FGIDs developed by consensus of experts and based on existing evidence. Finally, as we enter the new millennium, we offer recommendations for future studies that will help advance this growing field.

In this introductory article, I will review the rationale and limitations of a symptom-based diagnostic (Rome II) classification system, discuss the process through which the criteria and consensus information were developed, and briefly summarize the pathophysiological knowledge that is evolving about the FGIDs. More detailed information is provided in the other articles written by the 10 committees.

Rationale for symptom-based diagnostic criteria

The Rome II classification system is based on the premise that for each disorder there are symptom clusters that “breed true” across clinical and population groups. While not completely true (see Qualifications, below), this presumption provides a framework for identification of patients for research, which can be modified as new scientific data emerge. The rationale for classifying the FGIDs into symptom-based subgroups has three bases.7

The process of developing diagnostic criteria

The process for developing these criteria is a rigorous one. The consensus process was initiated by Professor Aldo Torsoli for the International Congress of Gastroenterology in Rome (Roma ’88). Professor Torsoli charged the committees19 to use a Delphi method20 of decision-making, which fosters a team effort to produce consistency in opinion, or consensus (although not necessarily total agreement) for difficult questions not easily tackled. In 1995, the Rome II Coordinating Committee took on the responsibility of carrying these activities further using a rigorous four year, 10-step process:

 (1) 

The Coordinating Committee identified individuals with international research and clinical expertise to chair each of the 10 committees. Each Chair was charged to develop a manuscript for this supplement and an expanded manuscript for an upcoming book.

 (2) 

Each Chair, in consultation with the Coordinating Committee, identified a Co-Chair and recruited an international panel of up to five additional members having similar clinical and investigative skills to create the manuscripts.

 (3) 

Each committee member produced a document in response to specific assignments given by the Chair and Co-Chair. Usually the task was to synthesize the literature regarding the physiological, psychological, diagnostic, and treatment aspects of a particular functional disorder or scientific content area.

 (4) 

Each Chair incorporated all documents into a manuscript that was sent to the entire committee for review.

 (5) 

This process of modification and re-review by the committee was repeated two more times over a two year period.

 (6) 

Each committee met for three days in June 1998 to revise the document, using the Delphi method.20 This face-to-face meeting led to consensus on the diagnostic criteria and scientific content.

 (7) 

Each Chair sent the revised document to at least six outside international experts and to scientists in the pharmaceutical industry for review and comment.

 (8) 

The committee Chairs responded to the reviewers’ comments either by modifying the manuscripts as requested, or providing a written response that addressed the reviewers’ concerns.

 (9) 

The revised manuscripts and the commentaries by the reviewers and authors were then sent to the Coordinating Committee who met in November 1998 and again in February 1999 to review these materials critically, and to submit critiques back to the authors.

(10)

Finally, when the document was completed, all members signed off their approval before it was returned back to the Coordinating Committee for a final check on content and style prior to submission for publication.

Observations on the functional gastrointestinal disorders

In proposing the diagnostic groupings listed in table 1, we recognize that, despite differences in location and symptom features, they share common features with regard to their motor and sensory physiology, central nervous system (CNS) relationships, and the approach to patient care. What follows are general observations and guidelines for these disorders.

A biopsychosocial conceptualization

As indicated by the findings summarized in the previous section, the links among psychosocial and physiological factors are essential for a full understanding of the mechanisms and varying presentations of the FGIDs. Figure 1 conceptualizes this biopsychosocial understanding of the relationship between psychosocial and physiological factors with functional gastrointestinal symptoms and the clinical outcome. Early in life, genetics and environmental influences (e.g., family attitudes toward bowel training or illness in general, major loss or abuse history, or exposure to an infection) may affect one’s psychosocial development (susceptibility to life stress, psychological state, coping skills, development of social support) or the development of gut dysfunction (abnormal motility or visceral hypersensitivity). In addition, the presence and nature of a FGID is determined by the interaction of psychosocial factors and altered physiology via the brain–gut axis. So, one individual afflicted with a bowel disorder, but with no psychosocial disturbances and good coping skills and social support, may not experience the symptoms as distressing enough to seek medical care. Another, having co-existent psychosocial disturbance, high life stress, and poor social support, may experience the symptoms as severe and unmanageable, may see physicians frequently, and have a generally poor outcome.

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Figure 1

A biopsychosocial conceptualization of the pathogenesis and clinical expression of the functional gastrointestinal disorders (FGID). CNS, central nervous system; ENS, enteric nervous system.

Based on the observations presented, it is no longer rational to try to discriminate whether physiological or psychologic factors produce pain or other bowel symptoms, dysmotility, or inflammation. Instead, the FGIDs seem to be understood in terms of dysregulation of brain–gut function, and the task is to determine the degree to which each is operative and remediable.

Concluding comments

It is with great pleasure and anticipation that we introduce this supplement on the functional gastrointestinal disorders, containing information on over two dozen adult and pediatric FGIDs, as well as supplementary information on the basic, physiologic and psychosocial aspects of these conditions. We hope that the information will make a difference in increasing awareness and knowledge relating to the diagnosis and care of patients with FGIDs. This supplement, and the book to follow (Rome II: The Functional Gastrointestinal Disorders published by Degnon Associates, 2000), which will contain more detailed information, are the culmination of four years of effort by over 60 internationally recognized investigators in the field. For further information, contactwww.romecriteria.org.

As new scientific data about these disorders accumulate, there will be a need to revise the diagnostic criteria and the information provided relating to the pathophysiology and treatment of these conditions. Therefore, we have set up a process for validation studies and other future activities of the Rome Committees that will permit ongoing review and modification of our current recommendations.