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

Background & Aims: 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.

Methods: 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.

Results: 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.

Conclusions: 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.