Severe childhood asthma linked to adult COPD

By Bianca Nogrady 
Persistent, severe asthma in childhood may be linked to an increased risk of chronic obstructive pulmonary disease (COPD) in later life, US research suggests. 

Researchers conducted an observational longitudinal follow up of 684 children with asthma who were enrolled in a randomised controlled trial of inhaled anti-inflammatory medication, classifying them according to patterns of lung-function growth based on regular FEV1 measurements. Their analysis suggested individuals who went on to develop COPD were much more likely to have shown a reduced pattern of FEV1 growth during the first three decades of life. 

Reduced growth in FEV1 was also associated with lower baseline FEV1 values, smaller bronchodilator response, and hyper-responsive airways at baseline, and was more common in men than women. 

Overall, 11% of participants met the criteria for COPD, whereas 49% showed reduced growth in lung function, either with or without early decline, according to the paper published in The New England Journal of Medicine. 

‘In the two groups with an early decline in lung function, the mean age when lung function began to decline was 21.1 years for participants with normal growth and 21.3 years for those with reduced growth, indicating that early decline is an important contributor to the long-term deficit in lung function that is frequently observed in patients with asthma,’ the researchers wrote. 

‘Our data support the hypothesis that both reduced growth and an early decline are trajectories leading to an asthma– COPD overlap syndrome and complement the recent observation that in older patients, a rapid decline in lung function can lead to COPD.’

Commenting on the study, Associate Professor Greg King said the study shows just how heterogeneous asthma in childhood can be, with some individuals having an excellent prognosis and others having more severe disease where impaired lung function persists and possibly even worsens into adulthood. 

However, he told Medicine Today that the notion that longstanding severe asthma in childhood might lead to the development of COPD was controversial. 

‘The basis of this is that COPD is defined as non-fully reversible airflow obstruction with an identifiable inhalation insult – usually cigarette smoking in Western societies – whereas in the case of asthma, there is no inhalation insult,’ said Associate Professor King, respiratory physician from the Woolcock Institute of Medical Research in Sydney. 

‘Clearly, there needs to be much more investment into research on the causes of reduced airway growth in childhood asthma and lung function impairment in adult asthma.’
N Engl J Med 2016; 374: 1842-1852.

Picture credit: © John Bavosi/SPL