Risk of irritable bowel syndrome after an episode of bacterial gastroenteritis in general practice: influence of comorbidities.

Given the discrepant estimates of incidence rates of irritable bowel syndrome (IBS) after gastroenteritis (GE), we performed a cohort study to quantify this risk in community subjects and to identify factors acting as modifiers of this effect. In a previous study, we identified patients aged 20-74 years with a first ever episode of bacterial GE during 1992-2001. We excluded patients with a history of bowel disease and cancer, resulting in a cohort of 5894 individuals with GE. From the same source population, a control group free of GE was sampled. We followed up the 2 cohorts to identify incident cases of IBS. A nested case-control analysis was performed to quantify the role of potential risk factors. During a mean follow-up period of 4.1 years, 1105 patients developed IBS. The incidence rate of IBS after an episode of bacterial GE was 98.2 per 10,000 person-years, and 45.3 per 10,000 person-years in the comparison cohort. The adjusted relative risk of IBS associated with bacterial GE was 2.2 (1.5-2.9) compared with the control cohort. The nested case-control analysis adjusting for additional risk factors produced similar results (odds ratio, 1.8; 95% confidence interval, 1.5-2.1). The risk of IBS after GE was increased significantly in patients with depression, anxiety, stress or sleep disorders, prior gastrointestinal morbidity, or prolonged use of antibiotics. The risk of IBS in community individuals after having bacterial GE was two fold greater in the general population. Pre-existing psychologic and gastrointestinal comorbidities independently increase this risk of developing IBS.