New research shows that adults with asthma may have an increased risk of developing chronic obstructive pulmonary disease (COPD).
According to a 20-year study published in the July issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians (ACCP), patients with asthma were 12 times more likely than nonasthmatics to develop COPD later in life.
"For many years, asthma and COPD have been regarded as distinct conditions, with separate clinical courses. However, over time, the two diseases may develop features that are quite similar. Our study shows a strong link between asthma diagnosis and the development of COPD, which suggests they may share a common background," said the article's lead author Graciela E. Silva, MPH, University of Arizona, College of Medicine, Tucson, AZ. "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." COPD is a collective name for a group of chronic lung diseases, including emphysema and chronic bronchitis, characterized by irreversible airflow limitation and permanent lung damage. Asthma is a chronic disease in which the airways become inflamed, causing airflow obstruction and difficulty breathing. Unlike COPD, it is thought that asthma does not lead to permanent lung damage and symptoms can usually be relieved spontaneously or with medication.
University of Arizona researchers assessed whether an active asthma diagnosis is a predictor of a future diagnosis of emphysema, chronic bronchitis, or COPD (emphysema and/or chronic bronchitis and pulmonary function test results less than 80 percent of predicted). Researchers analyzed survey data obtained from 3,099 Caucasian community subjects enrolled in the Tucson Epidemiologic Study of Airway Obstructive Disease between 1972 and 1973. Patients at least 20 years of age upon enrollment were initially assessed for asthma, allergies, and potential confounders, including age, sex, and smoking status. Of the patients, 192 currently had asthma (active asthma), 156 were previously diagnosed with asthma but no longer experienced symptoms (inactive asthma), and the remaining patients did not have asthma. All patients had negative findings for chronic bronchitis and emphysema at initial survey. Over the next 20 years, 12 periodic follow-up surveys and lung function tests were administered. Study results showed that patients with active asthma were 10 times more likely to acquire symptoms of chronic bronchitis, 17 times more likely to receive a diagnosis of emphysema, and 12.5 times more likely to develop COPD than patients without asthma. No association was found between inactive asthma and the lung conditions. Age and current smoking were significantly associated with an increased risk of acquiring COPD, emphysema, or chronic bronchitis.