A new study from the Royal Children's Hospital in Melbourne has shown that children with severe asthma have more than 30 times the risk of developing adult chronic obstructive lung disease (COPD) as adults compared to children without asthma.
"There is important epidemiological evidence to suggest that events in childhood that influence lung growth constitute a significant risk for COPD. The aim of this study was to describe the association between the pattern of childhood asthma and the risk of developing adult COPD in a longitudinal cohort," said lead author, Andrew Tai.
Subjects of the Melbourne Asthma Study were recruited at the age of seven, from a 1957 birth cohort and were assessed regularly until the age of 50.
At recruitment, subjects were classified as having no history of wheeze, intermittent asthma (such as viral-induced wheezing), persistent asthma (in the absence of illness), or severe asthma.
Of the surviving members of the original group, 197 answered a detailed questionnaire and underwent lung function testing for the current study.
Subjects who were classified as having severe asthma in childhood had an adjusted risk of COPD of 31.9 times that of children without asthma. Interestingly, children with mild asthma were not at increased risk of developing adult obstructive lung disease.
"At this stage, children with mild asthma are those who have symptoms of wheeze which are triggered primarily by respiratory infections. A majority [of children with mild asthma] remit by adolescence or adulthood," Dr. Tai said.
"However, children with more severe asthma features tend to have predisposing risk factors (like atopy) and continue to have symptoms of wheeze well into adult life.
"It is important to emphasize that the lung function decline in this group is not increased compared to those with mild or no asthma, as has been raised in some other studies.
"However, lung function in children with severe asthma are reduced in childhood years and decline in adult life to levels consistent with adult obstructive lung disease. Fundamentally, 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," Dr. Tai added.
The results will be presented at the ATS 2010 International Conference in New Orleans.