An episode of infectious gastroenteritis might be a factor in the onset of inflammatory bowel disease.
Dr. Chad K. Porter and his colleagues conducted a nested case-control study to determine whether the risk of IBD was higher in patients with a documented episode of infectious gastroenteritis (IGE). Using claims data from the Defense Medical Surveillance System (the main database for U.S. military medical data), the researchers identified 3,019 active-duty military personnel with IBD who served between 1999 and 2006.
Each patient was matched for time, sex, and age with four controls from the same population who did not have IBD. The mean age for both patients and controls was 34 years, and about 82% of both groups were male. Of the IBD patients, 72% were white, compared with 64% of the controls.
To reduce the possibility that the medical visit for IGE was actually the first presentation of IBD, the IGE must have occurred 6 months prior to IBD diagnosis, based on the average time from IBD presentation to diagnosis in 266 cases selected from the data set at random. Also excluded were patients with an irritable bowel syndrome (IBS) diagnosis within 6 months before the IGE visit.
Of all IBD patients, 1,720 had a diagnosis of ulcerative colitis and 1,037 had Crohn's disease. A diagnosis of pseudopolyposis colon was considered to be IBD but was not included in the subanalyses. Patients with both ulcerative co-litis and Crohn's were included in the overall analysis but not the subanalyses.
The authors used univariate and multivariate conditional logistic regression models to evaluate the relationship between IGE and all IBD, as well as between IGE and ulcerative colitis and Crohn's disease separately.
“A previous diagnosis of infectious gastroenteritis was significantly associated with an increased odds of inflammatory bowel disease” (odds ratio, 1.40), the authors wrote (Clin. Gastroenterol. Hepatol. 2008 September [doi:10.1053/j.gastro.2008.05.081]). Patients who had experienced IGE were slightly more likely to develop Crohn's disease (OR, 1.54) than ulcerative colitis (OR, 1.36).
In addition, patients with a prior diagnosis of IBS had a fivefold increased risk of IBD, compared with those who were never diagnosed with IBS. This association “could be due to IBS-like symptoms of undiagnosed [Crohn's disease], or [because] IBS actually predisposes individuals to the development of IBD,” they wrote.
When the analysis was restricted to patients without a prior IBS diagnosis, previous IGE remained significantly associated with Crohn's disease (OR, 1.48) and ulcerative colitis (OR, 1.39). The slight difference in risk between ulcerative colitis and Crohn's patients could be due to genetic predisposition and immunopathologic triggers, Dr. Porter of the Naval Medical Research Center, Silver Spring, Md., and his colleagues said.
Race was also linked with increased risk of developing IBD: Whites had a significantly higher risk (OR, 1.44), compared with blacks, Hispanics, Asians, and others.
The authors concluded that “the risk of IBD was greater in those with a prior episode of infectious diarrhea.” They suggested that “among genetically susceptible individuals, IBD may arise subsequent to an enteric infection due to an alteration of the gut epithelial barrier resulting in exposure to commensal and/or pathogenic microflora and disturbed adaptive and innate immune responses leading to disease.”
One limitation of the study was that patients with undiagnosed IBD may be more likely to access medical care for IGE, perhaps because IGE is more severe in these patients as a result of pathophysiological changes or insufficient immune response, Dr. Porter and his colleagues said.
This study is in concordance with previous research indicating that infectious gastroenteritis might contribute to an initiation of IBD among susceptible individuals through disruption of normal gut homeostasis, they wrote.
None of the authors had a financial conflict of interest regarding their study.