[Epidemiological studies in irritable bowel syndrome].

Irritable bowel syndrome (IBS) has gradually been understood from recent epidemiological studies. Overall prevalence of IBS varies between 5% and 20%. Constipation-predominant IBS is more common in women. IBS patients are more likely to show nongastrointestinal symptoms (somatization) and illness behaviors, especially in women. IBS patients have poor health-related quality of life. Although small numbers of subjects with IBS in the community visit physicians, socioeconomic impact caused by this disorder is not ignored in terms of direct health care costs and indirect effects including work absenteeism. It should be necessary to know these diverse aspects of such 'difficult' patients with IBS considering a bio- psycho- social model in clinical practice.