People with airway diseases, including asthma and chronic obstructive pulmonary disease (COPD), have a higher incidence of inflammatory bowel disease, such as Crohn's disease and ulcerative colitis, according to the findings of a new study.

The research, which is published online in the European Respiratory Journal, is the first population-based study to examine the association between airway diseases and the incidence of bowel disease. The news comes on World COPD Day, which aims to improve awareness and care of COPD.

The results showed that the incidence of Crohn's disease was 27% higher in people with asthma and 55% higher in people with COPD, compared to the general population. The incidence of ulcerative colitis was 30% higher in people with COPD compared to the general population.

Previous studies have suggested a link between the two conditions, which could be a result of common genetic and environmental factors, or similar inflammatory responses seen in the immune system. If the link is proven, it would have key implications for clinicians treating people with airway diseases.

Researchers used a health database to retrieve information on both airway disease and inflammatory bowel disease from 2001 to 2006. By using information on the prescriptions of both asthma and COPD medications during that time period, the researchers identified 136,178 people with asthma and 143,904 people with COPD. Data from doctor and hospital visits was then used to identify the bowel conditions, Crohn's disease and ulcerative colitis, in both groups.

Dr Paul Brassard, lead author of the study from the Lady Davis Institute for Medical Research of the Jewish General Hospital in Montreal, Canada, said: "These findings have important implications for the early detection of inflammatory bowel disease in airway disease patients. Although a link has previously been suggested, this is the first study to find significantly increased rates of inflammatory bowel disease incidence in people with asthma and COPD. If we can confirm a link between the two conditions it will help diagnose and treat people sooner, reducing their symptoms and improving their quality of life."