Association of inflammatory bowel disease with asthma risk: A nationwide cohort study

Objective: We evaluated the risk of asthma development in adult patients with inflammatory bowel disease (IBD) in a nationwide population. Methods: A retrospective cohort study was conducted by using data retrieved from the Taiwan National Health Insurance Research Database. Patients, ages 20 year or older, with newly diagnosed IBD between 2000 and 2005 were identified and randomly frequency-matched (based on sex, age, and index year) with four times the number of enrollees without IBD from the general population. Both cohorts were followed up until the end of 2011 to examine the incidence of asthma. Cox proportional hazard regression analysis was used to measure the hazard ratios (HR) of asthma in the IBD cohort compared with that in the non-IBD cohort. Results: The IBD and non-IBD cohorts comprised 5260 patients with IBD and 21,040 participants, respectively. After adjustment for covariates, the IBD cohort exhibited a 1.50-fold increased risk for asthma (HR 1.50, [95% confidence interval {CI}, 1.32-1.71]). Further analysis according to the two major forms of IBD revealed that the adjusted HR of asthma was 1.46 (95% CI, 1.03-2.07) and 1.50 (95% CI, 1.31-1.72) in patients with ulcerative colitis and Crohn's disease, respectively, compared with the non-IBD cohort. Conclusion: After adjustment for comorbidities, patients with IBD were associated with a higher subsequent risk of asthma.