NEW YORK (Reuters Health) - In a 20-year study, people with asthma were about 12 times more likely to develop chronic obstructive pulmonary disease (COPD) than people who did not have asthma, according to a new report.
"For many years, asthma and COPD have been regarded as distinct conditions, with separate clinical courses," lead author Graciela E. Silva, from the University of Arizona in Tucson, said in a statement.
While both conditions cause difficulty breathing, asthma has been considered to be reversible whereas COPD, which covers a number of diseases, is seen as irreversible. However, writes Silva, "Our study shows a strong link between asthma diagnosis and the development of COPD, which suggests they may share a common background."
The findings are based on a study, published in the medical journal Chest, of 3099 adult subjects who completed respiratory questionnaires and underwent lung function testing several times during a 20-year period.
Active asthma was associated with an increased risk of COPD compared with inactive disease or normal respiratory status, the researchers found.
Compared with non-asthmatic subjects, those with active asthma were 10 times more likely to develop chronic bronchitis and 17 times more likely to develop emphysema, Silva's team reports.
Moreover, this pattern held true even after taking into account smoking history and other factors that could affect the risk.
The authors note that further studies are needed to clarify exactly how asthma may lead to the development of COPD.
SOURCE: Chest, July 2004.