Methods: In a previous study, we identified patients aged 20 to 74 years with a first ever episode of infectious GE during 1992-2001. We excluded patients with history of bowel disease and cancer resulting in a cohort 5,894 individuals with documented bacterial GE. From the same source population, an age, sex and calendar time-matched control group free of gastroenteritis was sampled. We followed the two cohorts to identify incident cases of IBS. A secondary nested case-control analysis was performed with all incident cases of IBS to further quantify the role of potential risk factors.

Results: We ascertained 1,105 patients developing IBS during a mean follow-up of 4.1 years. 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 to the control cohort. A nested case-control analysis adjusting for a number of additional risk factors produced similar results: Odds ratio: 1.8 (95% CI: 1.5-2.1). The risk of IBS following an episode of bacterial GE was significantly increased in patients with previously documented depression, anxiety, stress or sleep disorders, prior gastrointestinal morbidity, or prolonged use of antibiotics.

Conclusions: The risk of IBS in community individuals after having an episode of bacterial GE is twice the one in the general population. Preexisting psychological and gastrointestinal comorbidities independently increase this risk.