May 17, 2010 -- Children who suffer from severe, persistent asthma are nearly 32 times more likely to develop chronic obstructive lung disease (COPD) in adulthood, according to a study spanning nearly half a century.
That conclusion is based on data from the Melbourne Asthma Study, which includes children born in 1957 who were recruited at age 7 and tracked until their 50th birthdays. At the time they were recruited, the children were placed into four groups: those who did not experience wheezing or asthma symptoms, those who experienced occasional asthma such as wheezing associated with a viral respiratory infection, those who had persistent asthma not associated with a viral respiratory infection, and those who had severe, persistent asthma.
The objective was to see which children developed COPD as adults.At age 50, 197 of the surviving participants answered a detailed questionnaire and underwent lung function testing.
COPD was identified in 28 of the participants and was found to be more common among males. There was a direct correlation between the severity of the asthma as a child and the incidence of COPD as an adult. The study results showed:
15 of the 28 COPD patients had a history of severe, persistent asthma as a child.
8 had persistent asthma as a child.
4 had occasional asthma as a child.
Only one person who developed COPD did not have any wheezing or asthma as a child.
The study also showed that children with mild or occasional asthma were not at an increased risk of developing COPD.
The findings were presented by study researcher Andrew Tai of the Royal Children's Hospital in Melbourne, Australia, at the American Thoracic Society International Conference in New Orleans.
"There is important epidemiological evidence to suggest that events in childhood that influence lung growth constitute a significant risk for COPD," said Tai. "We believe that this severe asthma group start with a lesser baseline lung function and gradually deteriorate to the levels consistent with a diagnosis of COPD. At this stage, there is no data on when airway remodeling occurs in children and hence, its impact on lung function, but there is an emerging relationship between childhood severe asthma and adult obstructive lung disease."
COPD is a progressive disease in which lung function becomes steadily impaired and airways lose their elasticity, making it increasingly difficult to breathe. Cigarette smoking is the leading cause of COPD, but pollution exposure can also contribute to COPD risk.
The study was performed on a group of children recruited during the 1960s, when many of the asthma treatments, such as anti-inflammatory drugs, were not available. The researchers note that while they do not understand the biological connection between childhood asthma and adulthood COPD, the findings do suggest that abnormalities in lung function may be established during childhood and lead to irreversible airway obstruction in adulthood. Tai and his colleagues said that greater surveillance and earlier treatment to help prevent airway remodeling could potentially mitigate COPD complications later in life.