Objective: Several studies have suggested significant associations between environmental factors and the risk of developing inflammatory bowel disease [IBD]. However, data supporting the role of antibiotics are conflicting. The aim of this study was to evaluate the association between antibiotic use and new-onset IBD.

Methods: We conducted a population-based case-control study using the Rochester Epidemiology Project of Olmsted County, Minnesota. We identified 736 county residents diagnosed with IBD between 1980 and 2010 who were matched to 1472 controls, based on age, sex and date of IBD diagnosis. Data on antibiotic use between 3 months and 5 years before IBD diagnosis were collected. Logistic regression models were used to estimate associations between antibiotic use and IBD, and were expressed as adjusted odds ratio [AOR] with 95% confidence interval [CI].

Results: Antibiotic use occurred in 455 IBD cases [61.8%] and 495 controls [33.6%] [p < 0.001]. In multivariate analysis, there were statistically significant associations between antibiotic use and new-onset IBD [AOR, 2.93; 95% CI, 2.40-3.58], Crohn's disease [CD] [AOR, 3.01; 2.27-4.00] and ulcerative colitis [UC] [AOR, 2.94; 95% CI, 2.23-3.88]. A cumulative duration of antibiotic use ≥ 30 days had the strongest AOR [6.01; 95% CI, 4.34-8.45]. AOR for those receiving antibiotics under the age of 18 years was 4.27 [95% CI, 2.39-7.91], 2.97 for age 18-60 years [2.36-3.75] and 2.72 for age > 60 years [1.60-4.67].

Conclusions: This population-based case-control study suggests a strong association between antibiotic use and the risk of both new-onset CD and new-onset UC. The risk was increased among all age-onset IBD.