Antibiotic use as a risk factor for irritable bowel syndrome: Results from a nationwide, case-control study

Background: The microbiome plays an important role in the pathophysiology of irritable bowel syndrome (IBS). Antibiotic use can fundamentally alter gut microbial ecology. We examined the association of antibiotic use with IBS in a large population-based investigation.Methods: A case-control study with prospectively collected data on 29,111 adult patients diagnosed with IBS in Sweden between 2007 and 2016 matched with 135,172 controls. Using a comprehensive histopathology cohort, the Swedish Patient Register, and the Prescribed Drug Register, we identified all consecutive cases of IBS in addition to cumulative antibiotic dispensations accrued until 1 year prior to IBS (exclusionary period) for cases and time of matching for up to five general population controls matched on the basis of age, sex, country and calendar year. Conditional logistic regression estimated multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the risk of IBS.Results: Patients with IBS (n = 29,111) were more likely than controls (n = 135,172) to have used antibiotics up to 1 year prior to diagnosis (74.9% vs. 57.8%). After multivariable adjustment, this translated to a more than twofold increased odds of IBS (OR 2.21, 95% CI 2.14-2.28) that did not differ according to age, sex, year of IBS diagnosis or IBS subtype. Compared to none, 1-2 (OR 1.67, 95% CI 1.61-1.73) and >= 3 antibiotics dispensations (OR 3.36, 95% CI 3.24-3.49) were associated with increased odds of IBS (p for trend <0.001) regardless of the antibiotic class.Conclusions: Prior antibiotics use was associated with an increased odds of IBS with the highest risk among people with multiple antibiotics dispensations.