Scope of the problem of functional digestive disorders.

Functional dyspepsia and the irritable bowel syndrome (IBS) are amongst the most widely recognised functional gastrointestinal disorders. Symptom based diagnostic criteria have been developed and refined for the syndromes (the Rome criteria) and these are now widely applied in clinical research. Both functional dyspepsia and IBS are remarkably prevalent in the general population, affecting approximately 20% and 10% of persons, respectively. The prevalence is stable from year to year because the onset of these disorders is balanced by their disappearance in the population. Clinically useful predictors of the course of these disorders have not been identified. Approximately one third of persons with functional dyspepsia concurrently have IBS. In most studies from Western countries, it has been shown that only a minority with functional dyspepsia and IBS present for medical care; the factors that explain consultation behaviour remain inadequately defined although fear of serious disease and psychological distress may be important. The majority of patients diagnosed as having functional dyspepsia or IBS continue to have symptoms long term with a significant impact on quality of life. The indirect costs of the functional gastrointestinal disorders greatly outweigh the direct costs but overall these conditions are responsible for a major proportion of health care consumption. Rational management of the functional gastrointestinal disorders will only follow a better understanding of the natural history of these conditions.