Irritable bowel syndrome: more than abdominal pain and bowel habit abnormalities

Although irritable bowel syndrome (IBS) can be defined using few symptoms, principal symptoms alone may be inadequate in monitoring disorder severity. Secondary analysis of a published data set was performed to determine if more inclusive symptom measures would better reflect the burden of this disorder.

From a prospective naturalistic study of 213 patients meeting Rome II criteria, all the data were used from daily questionnaires recorded for 4 weeks, and repeated again after an interval of 4 weeks. The total number of 11 symptoms and intensity grading score of each symptom were analyzed alongside individual symptom intensities by principal component analysis.

The trend accounting for the most variance was explained by the intensity of all symptoms together. The second largest trend was explained by differences between IBS bowel habits (constipation and diarrhea). The 2 constipation and 4 diarrhea symptoms closely correlated within each group, but the category of other symptoms were not correlated directly with either, and represent a separate dimension. Other symptoms (pain/discomfort, abdominal uneasiness, flatulence/distension, incomplete evacuation, pain or burning in the stomach) correlated more highly with disease intensity than either constipation or diarrhea symptoms. The sum of all symptoms and their intensity was consistent over each week, although the relative intensity of individual symptoms was more variable. Investigator measures of disease intensity underestimated that reported by patients.

Non-bowel habit symptoms include more than abdominal pain and discomfort, and contribute to the largest component of the total symptom burden. Thus, more than bowel habits and abdominal pain drive IBS symptom severity.