Objectives: It has been suggested that the variation in the prevalence of irritable bowel syndrome (IBS) may be due to the application of different diagnostic criteria. New criteria for IBS have been proposed (Rome II). It is unknown whether persons meeting different criteria for IBS have similar psychological and symptom features. The aim of this study was to measure the prevalence of IBS according to Manning and Rome definitions of IBS and to evaluate the clinical and psychological differences between diagnostic categories.
Methods: A total of 4500 randomly selected subjects, with equal numbers of male and female subjects aged > or = 18 yr and representative of the Australian population, took part in this study. Subjects were mailed a questionnaire (response rate, 72%). Characteristics measured were gastrointestinal symptoms over the past 12 months, neuroticism and extroversion (Eysenck Personality Questionnaire), anxiety and depression (Delusions-Symptoms-States Inventory), mental and physical functioning (SF-12), and somatic distress (Sphere).
Results: The prevalence for IBS according to Manning, Rome I, and Rome II was 13.6% (95% confidence interval [CI] = 3.5-5.1%), 4.4% (CI 6.0-7.8%), and 6.9% (CI 12.3-14.8%), respectively [corrected]. Only 12 persons with Rome I did not also meet Rome II criteria; 196 persons with Manning criteria did not meet Rome II cut-offs. Having IBS regardless of which criteria were used was significantly associated with psychological morbidity, but psychological factors were not important in discriminating between diagnostic categories. However, pain and bowel habit severity independently discriminated between diagnostic groups.
Conclusions: IBS is a relatively common disorder in the community. The new Rome II criteria may be unnecessarily restrictive in practice.