Long-term Clinical Course of Post-infectious Irritable Bowel Syndrome After Shigellosis: A 10-year Follow-up Study

ABSTRACT

BACKGROUND/AIMS: A limited number of studies are available regarding the long-term natural history of post-infectious irritable bowel syndrome (PI-IBS). We aimed to investigate the long-term clinical course of PI-IBS. METHODS: A prospective cohort study was conducted from a 2001 shigellosis outbreak in a Korean hospital with about 2000 employees. A cohort of 124 hospital employees who were infected by Shigella sonnei due to contaminated food in the cafeteria, and 105 sex- and age-matched, non-infected, controls were serially followed for their bowel symptoms by questionnaire surveys for 10 years. RESULTS: The Shigella-infected cohort showed significantly higher odds ratio for irritable bowel syndrome (IBS) at 1-year (11.90; 95% CI, 1.49-95.58) and 3-year (3.93; 95% CI, 1.20-12.86) follow-up, compared to their controls. However, corresponding odds ratio for PI-IBS was not significantly increased at 5-year (1.88; 95% CI, 0.64-5.54) and 8-year (1.87; 95% CI, 0.62-5.19) follow-up. At 10-year follow-up survey, the prevalence of IBS was similar for the Shigella-infected cohort and their controls (23.3% versus 19.7%, P = 0.703). Risk factors which were independently associated with PI-IBS among the Shigella-infected cohort included younger age, previous history of functional bowel disorder, and longer duration of diarrhea at baseline. CONCLUSIONS: Patients who were infected by Shigella sonnei experienced significantly increased risk of IBS until 3 years after shigellosis, and modestly increased risk until 8 years, but showed similar risk of IBS with uninfected controls at 10 years post-infection. PI-IBS is quite a chronic disorder, and follows a long-term natural course.