Using health databases from Alberta, Canada, the study examined 5,464 IBD patients (3,087 with Crohn’s disease and 2,377 with ulcerative colitis) and 402,800 controls. Researchers then looked at previous diagnosis of asthma in each of these groups.
Results showed that there was a statistically significant chance of developing Crohn’s disease in patients previously diagnosed with asthma, regardless of the age at diagnosis of Crohn’s.
Previous diagnosis with asthma was also significantly associated with the development of ulcerative colitis, but only in individuals diagnosed with ulcerative colitis before the age of 16 (3-16) and over the age of 40. There was no association between asthma and ulcerative colitis among individuals diagnosed between ages 17 and 40.
Taken together, these results indicate that patients with asthma are at a higher risk of developing Crohn’s disease, and early and late onset ulcerative colitis.
The study “Asthma is Associated With Subsequent Development of Inflammatory Bowel Disease: A Population-Based Case-Control Study” was published in the journal Clinical Gastroenterology and Hepatology.
The researchers built on previous studies that showed there is an association between IBD and respiratory disorders, including asthma. Since asthma is usually diagnosed at an earlier stage than IBD, the researchers hypothesized that there is an association between asthma and the subsequent IBD diagnosis — including Crohn’s disease and ulcerative colitis — later in life.
Although the mechanisms that led to the observed association between asthma and IBD in the study are unknown, similarities in the underlying structure of lung and intestinal tissues are thought to play a role.
The results of the study suggest that there are differences in IBD pathogenesis according to age and gender. Women were found to be more likely to develop Crohn’s disease, while those over age 40 had a lower chance of developing ulcerative colitis compared with age-matched men.
The authors point out a few limitations of their study, such as the examined databases not containing enough data regarding so-called unmeasured confounders, such as smoking.
The team emphasizes that among the clinical implications of their study is that it “may serve as a red flag to help identify patients presenting with chronic gastrointestinal symptoms that may benefit from priority early referrals to gastroenterologists.”
They conclude by saying that “future studies are necessary to determine the mechanisms through which asthma and IBD are related.”