Long-term Prognosis of Postinfectious Irritable Bowel Syndrome (Gut 2010;59:605-611)

Abstract

Sum m ary Marshall et al 1 has reported a study entitled "Eight year prognosis of postinfectious irritable bowel syndrome following waterborne bacterial dysentery" in the May issue of Gut 2010. This report was a cohort study from the population of Walkerton Health Study, of which participants were residents of Walkerton at the time of the outbreak in May 2000. They were invited for annual assessments of a postinfectious irritable bowel syndrome (PI-IBS) study at a research clinic until 2008. A modified Bowel Disease Questionnaire was used to diagnose IBS by Rome I criteria and to identify IBS subtypes. Of 4,561 Walkerton Health Study participants, 1,166 were eligible for this study (688 females , mean age 46.2 years). The prevalence of IBS among 742 eligible subjects who suffered acute gastroenteritis during the outbreak declined from 28.3% after 2-3 years from the infection to 15.4% after 8 years, but it remained significantly increased compared with controls who did not have history of acute gastro-enteritis (OR, 3.12; 95% CI, 1.99-5.04). Independent risk factors for PI-IBS at 8 years included female gender, younger age, prior anxiety/depression and fever or weight loss during the acute enteric illness. Authors have concluded that acute gastroenteritis could trigger IBS symptoms which persisted for at least 8 years, and the characteristics of the host and acute enteric illness could predict the long-term risk of PI-IBS. Com m ent It is important to study PI-IBS since its underlying mechanisms will help us understand other subtypes of IBS. Although most patients with infectious enteritis recover rapidly without any residual symptoms, some have persistent symptoms for many years and meet the criteria for a diagnosis of IBS. Prospective studies have shown the percentage of infected individuals who develop PI-IBS to vary from 3.7% to 36%. 2 Present report is the follow-up of study from the Walkerton outbreak. 3 This study is the largest and longest prospective community study of PI-IBS ever published. As the authors mentioned, the results can help clinicians to understand the long-term clinical features and to counsel patients on their long-term risk of PI-IBS. Over 8 years of follow-up, the overall prevalence of PI-IBS was 15.4%, which was statistically higher than that of the controls. This implies that most patients with PI-IBS can be improved although a significant minority experiences symptoms which might persist for a long-term period. Therefore, assess