Review article: the incidence and risk factors for irritable bowel syndrome in population-based studies

Many cross-sectional surveys have reported the prevalence of irritable bowel syndrome (IBS), but there have been no recent systematic review of data from all studies to determine its global prevalence and risk factors. MEDLINE, EMBASE, and EMBASE Classic were searched (until October 2011) to identify population-based studies that reported the prevalence of IBS in adults (≥15 years old); IBS was defined by using specific symptom-based criteria or questionnaires. The prevalence of IBS was extracted for all studies and based on the criteria used to define it. Pooled prevalence, according to study location and certain other characteristics, odds ratios (ORs), and 95% confidence intervals (CIs) were calculated. Of the 390 citations evaluated, 81 reported the prevalence of IBS in 80 separate study populations containing 260,960 subjects. Pooled prevalence in all studies was 11.2% (95% CI, 9.8%-12.8%). The prevalence varied according to country (from 1.1% to 45.0%) and criteria used to define IBS. The greatest prevalence values were calculated when ≥3 Manning criteria were used (14%; 95% CI, 10.0%-17.0%); by using the Rome I and Rome II criteria, prevalence values were 8.8% (95% CI, 6.8%-11.2%) and 9.4% (95% CI, 7.8%-11.1%), respectively. The prevalence was higher for women than men (OR, 1.67; 95% CI, 1.53-1.82) and lower for individuals older than 50 years, compared with those younger than 50 (OR, 0.75; 95% CI, 0.62-0.92). There was no effect of socioeconomic status, but only 4 studies reported these data. The prevalence of IBS varies among countries, as well as criteria used to define its presence. Women are at slightly higher risk for IBS than men. The effects of socioeconomic status have not been well described. Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.

Irritable bowel syndrome (IBS) is a functional gastrointestinal disease with a high population prevalence. The disorder can be debilitating in some patients, whereas others may have mild or moderate symptoms. The most important single risk factors are female sex, younger age and preceding gastrointestinal infections. Clinical symptoms of IBS include abdominal pain or discomfort, stool irregularities and bloating, as well as other somatic, visceral and psychiatric comorbidities. Currently, the diagnosis of IBS is based on symptoms and the exclusion of other organic diseases, and therapy includes drug treatment of the predominant symptoms, nutrition and psychotherapy. Although the underlying pathogenesis is far from understood, aetiological factors include increased epithelial hyperpermeability, dysbiosis, inflammation, visceral hypersensitivity, epigenetics and genetics, and altered brain-gut interactions. IBS considerably affects quality of life and imposes a profound burden on patients, physicians and the health-care system. The past decade has seen remarkable progress in our understanding of functional bowel disorders such as IBS that will be summarized in this Primer.

IBS affects 5-11% of the population of most countries. Prevalence peaks in the third and fourth decades, with a female predominance. To provide a guide for the assessment and management of adult patients with irritable bowel syndrome. Members of the Clinical Services Committee of The British Society of Gastroenterology were allocated particular areas to produce review documents. Literature searching included systematic searches using electronic databases such as Pubmed, EMBASE, MEDLINE, Web of Science, and Cochrane databases and extensive personal reference databases. Patients can usefully be classified by predominant bowel habit. Few investigations are needed except when diarrhoea is a prominent feature. Alarm features may warrant further investigation. Adverse psychological features and somatisation are often present. Ascertaining the patients' concerns and explaining symptoms in simple terms improves outcome. IBS is a heterogeneous condition with a range of treatments, each of which benefits a small proportion of patients. Treatment of associated anxiety and depression often improves bowel and other symptoms. Randomised placebo controlled trials show benefit as follows: cognitive behavioural therapy and psychodynamic interpersonal therapy improve coping; hypnotherapy benefits global symptoms in otherwise refractory patients; antispasmodics and tricyclic antidepressants improve pain; ispaghula improves pain and bowel habit; 5-HT(3) antagonists improve global symptoms, diarrhoea, and pain but may rarely cause unexplained colitis; 5-HT(4) agonists improve global symptoms, constipation, and bloating; selective serotonin reuptake inhibitors improve global symptoms. Better ways of identifying which patients will respond to specific treatments are urgently needed.