Irritable bowel syndrome (IBS) is a heterogeneous condition characterized by the presence of abdominal discomfort or pain and bowel habit alterations: constipation (C-IBS), diarrhea (D-IBS), or alternating C and D (A-IBS). Its clinical course is poorly known.
Objectives: (i) To compare bowel habit subtypes distribution in IBS according to sample origin and diagnosis criteria; (ii) To evaluate IBS temporal patterns based on follow-up studies.
Methods: A literature search (1966-2003) was conducted in the MEDLINE and EMBASE databases. A total of 72 studies were found and 22 were finally selected.
Results: Population-based studies from the United States (Manning) found similar distribution among C-IBS, D-IBS, and A-IBS, while European studies (Rome I, Rome II, or self-reporting) showed either C-IBS or A-IBS as the most prevalent subtypes. Primary care office-based studies (Rome I or Rome II) showed A-IBS as the most prevalent group. Gastroenterology specialized office-based studies found either C-IBS or D-IBS as the most frequently reported subtype. Prospective follow-up investigations showed that the most frequent IBS temporal pattern profile consists of mild to moderate symptoms appearing in cluster in an intermittent way, about once a week, and lasting 2-5 days on average.
Conclusion: IBS clinical subtypes distribution differs depending on the population evaluated, the geographical location, and the criteria employed to define IBS and bowel habit subtypes. In most cases, clinical course is characterized by the presence of mild-to-moderate symptoms appearing sequentially. Prospective studies, using clear and stable diagnostic criteria and subtype definitions, and based on daily data collection should further characterize IBS clinical course.