Authors: Drossman DA, Morris CB, Hu Y, Toner BB, Diamant N, Leserman J, Shetzline M, Dalton C, Bangdiwala SI.

Institution: UNC Center for Functional GI and Motility Disorders, University of North Carolina at Chapel Hill, Room 1110 Burnett-Womack CB#7080, Chapel Hill, North Carolina 27599-7080, USA.

Background: Irritable bowel syndrome (IBS) is subtyped as IBS with diarrhea (IBS-D) or IBS with constipation (IBS-C) based on Rome II guidelines. The remaining group is considered as having mixed IBS (IBS-M). There is no standard definition of an alternator (IBS-A), in which bowel habit changes over time. Our aim was to use Rome II criteria to prospectively assess change in bowel habit for more than 1 year to understand IBS-A.

Results: At baseline, 36% had IBS-D, 31% IBS-M, and 34% IBS-C. Except for stool frequency, there were no differences between groups. While the proportion of subjects in each subgroup remained the same over the year, most individuals (more than 75%) changed to either of the other 2 subtypes at least once. IBS-M was the least stable (50% changed out by 12 weeks). Patients were more likely to transition between IBS-M and IBS-C than between IBS-D and IBS-M. Notably, only 29% switched between the IBS-D and IBS-C subtypes over the year.

Conclusions: While the proportion of subjects in each of the IBS subtypes stays the same, individuals commonly transition between subtypes, particularly between IBS-M and IBS-C. We recommend that IBS-A be defined as at least one change between IBS-D and IBS-C by Rome II criteria over a 1-year period.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15765393&query_hl=39&itool=pubmed_docsum

Authors: Mearin F, Baro E, Roset M, Badia X, Zarate N, Perez I.

Institution: Institute of Functional and Motor Digestive Disorders, Centro Medico Teknon, Barcelona, Spain.

Objectives: The clinical course of irritable bowel syndrome (IBS) remains poorly known. In 209 IBS patients meeting Rome II criteria (137 females and 72 males) we evaluated: (1). changes in frequency and intensity of abdominal pain/discomfort, abnormal number of bowel movements, loose or watery stools, defecatory urgency, hard or lumpy stools, straining during bowel movements, and feeling of incomplete evacuation); (2). use of resources, HRQoL, and psychological well being.

Results: High-intensity symptoms were present on more than 50% of the days. Sixty-one percent were classified in the same IBS subtype on both occasions (kappa= 0.48), while 49% had the same symptom predominance and intensity (kappa= 0.40). The greatest instability was observed among diarrhea (D-IBS) and constipation (C-IBS) subtypes: only 46% and 51% remained in the same pattern with a tendency to shift to alternating diarrhea/constipation subtype (A-IBS); however, practically no patient changed from D-IBS to C-IBS, or vice versa.

The most reliable symptom characteristic was frequency, followed by intensity and number of episodes. Symptom frequency and intensity were directly related to resource use and HRQoL impairment.

Conclusions: IBS symptoms are instable over time and variables in intensity. Many patients with D-IBS or C-IBS move to A-IBS; however, shift from D-IBS to C-IBS, or vice versa, is very infrequent.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14687152&dopt=Citation