Asthma and the inflammatory bowel diseases (IBD) each arise through complex interactions between genetic and environmental factors, and share many environmental risk factors.
Dr Gilaad Kaplan and colleagues from Canada examined the association between asthma and Crohn’s disease or ulcerative colitis.
The researchers performed a population-based case–control study using health administrative data from the province of Alberta, Canada. The odds of a diagnosis of asthma preceding the diagnosis of either Crohn’s disease or ulcerative colitis were compared with the odds of diagnosis of asthma among persons without IBD using logistic regression.
Effect measure modification by age at diagnosis of IBD was tested using a likelihood ratio test.
|A diagnosis of asthma was associated with increased odds of incident Crohn’s disease|
|Clinical Gastroenterology & Hepatology|
A diagnosis of asthma was associated with increased odds of incident Crohn’s disease.
The research team observed no effect measure modification for age at diagnosis for Crohn's disease.
However, the team observed effect measure modification by age at diagnosis for ulcerative colitis, with an adjusted OR of 1.5 among individuals diagnosed at an age of 16 years or less, and an adjusted odds ratio of 1.6 among individuals diagnosed at an age older than 40 years.
The researchers noted no association between asthma and ulcerative colitis among individuals diagnosed between ages 17 and 40.
Dr Kaplan's team concludes, "In a population-based case–control study, we associated asthma with Crohn’s disease, and with early and late-onset ulcerative colitis."