Though many children with persistent asthma get better as they grow up, some might develop chronic obstructive pulmonary disease (COPD) in early adulthood, according to a new study.
People with the poorest lung function and reduced lung growth faced the highest risk for developing COPD, a chronic progressive condition that made it hard to breathe, the researchers said.
"Study participants were children with mild-to-moderate persistent asthma, which places them among the most severe 30 or 40 per cent of all childhood asthmatics. Among this group, serious airway obstruction is an early life possibility," said researcher Michael McGeachie, Health Day reported.
"There may be interventions that can help mitigate these risks, although we do not specifically identify any," said McGeachie, an instructor in medicine at Harvard Medical School and Brigham and Women's Hospital in Boston.
The investigators noted a number of limitations to the study and one was that it could not prove a cause-and-effect relationship. The other was that longer-term follow-up was needed to see how these [lung function] changes affected the health of the children over time. For instance, it was possible that in early adulthood, any declines in lung health might plateau, the study authors suggested.
The report was published yesterday in the New England Journal of Medicine.
Brigham and Women's Hospital said in a press release, ''This work tells us that persistent childhood asthma can develop into COPD, something that up until now has not been well described,'' said Scott T Weiss, MD, one of the paper's senior authors and co-director of the Systems Genetics and Genomics Section of the BWH Channing Division of Network Medicine.
''Children who had low lung function at the start of the trial followed a series of predicted growth patterns: most had reduced lung growth with time and a significant number would go on to meet the criteria for COPD.''
The study followed 684 participants in the Childhood Asthma Management Program (CAMP) from ages 5-12 until they were at least 23 years old. Each participant reported once a year to one of eight research centres around the US and Canada to complete lung function measurements like spirometry, a test that records how much air a participant can breathe out in one second.
With these annual recordings, the researchers were able to characterise the patterns of growth in asthmatics' lung function. By the end of the study, 11 per cent met the criteria for COPD, a progressive disease that makes breathing difficult.
In addition to low lung function at the start of the study, being male also predicted worse outcomes, but this is likely a consequence of higher asthma prevalence in boys. By early adulthood, 75 per cent of the children with persistent asthma displayed an early decline in lung function and/or reduced lung growth. Treatment did not change these patterns.
''It is astonishing,'' said co-senior author Robert C Strunk, MD, professor of paediatrics at Washington University School of Medicine, who died unexpectedly 28 April. ''For people barely into adulthood to already have COPD is terrible. As the COPD evolves, they are likely to have health problems that will make it difficult to participate in normal day-to-day responsibilities such as holding a job.''
''With this understanding, physicians need to identify at-risk children earlier and counsel them about potential preventative measures. Since asthma itself is a risk factor for developing COPD, these patients should be advised against risk related environmental exposures, like smoking, that could intensify their symptoms and increase their COPD risk,'' said Weiss. ''It is important that we recognise this link between persistent childhood asthma and COPD as a potential problem and focus on prevention efforts.''