"Our study shows a strong link between asthma diagnosis and the development of COPD, which suggests they may share a common background," says researcher Graciela E. Silva, MPH, of the University of Arizona's College of Medicine in Tucson, in a news release. "It is possible that factors such as smoking and repeated episodes of acute bronchitis may facilitate the evolution of asthma into COPD, but the process by which asthma and COPD become comorbid conditions is not clear."
Asthma Linked to Increased COPD Risk
In the study, published in the July issue of Chest, researchers tracked a group of about 3,000 people who enrolled in the Tucson Epidemiologic Study of Airway Obstructive Disease from 1972 to 1973. The participants were evaluated at the start of the study for asthma and other health conditions -- such as allergies and smoking status -- and then followed for 20 years.
Researchers found that people with active asthma had a significantly higher risk of chronic lung diseases later in life. Compared to adults without asthma, adults with asthma were:
- 17 times more likely to be diagnosed with emphysema
- 10 times more likely to develop symptoms of chronic bronchitis
- 12.5 times more likely to develop COPD
Smoking and advanced age also significantly increased the risk of being diagnosed with COPD or another chronic lung disease.
"Although most people living with COPD have a history of smoking, the majority of smokers do not develop COPD later in life, suggesting that other factors, such as genetic, occupational, or environmental conditions, convey significant risks," says Silva.
Researchers say that for people with asthma, minimizing exposure to risk factors like tobacco smoke and air pollution may delay or help prevent the development of COPD. Using effective anti-inflammatory therapy at the start of asthma symptoms may also decrease the likelihood of COPD developing years later.
No increase in risk of chronic lung disease was found in people who had a diagnosis of asthma but were no longer experiencing symptoms.
"Although there is no cure for COPD, early detection is critical in slowing disease progression," says Richard S. Irwin, MD, president of the American College of Chest Physicians, in the release. "Understanding the relationship between COPD and other chronic lung diseases, such as asthma, may lead to early disease detection, as well as more effective treatments for patients with COPD."