Asthma Research Shows Lung Function Set Early
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Preschoolers with asthma symptoms have their level of lung function set by the age of six and don’t change much for at least 10 years, researchers here say.
The finding, derived from a long-term follow-up of 826 children in a population-based birth cohort here, eases fears that asthmatic children face years of deteriorating lung function, according to Wayne Morgan, M.D., of the University of Arizona Health Sciences Center.
On the other hand, Dr. Morgan and colleagues said, the research strongly suggests that what happens during the first six years of life determines the expression of asthma and the level of lung function that will be achieved during childhood and into early adult life.
“If we’re going to prevent it, we have to intervene earlier,” said Dr. Morgan, who led the study. Results of the Tucson Children’s Respiratory Study were published in the Nov. 15 issue of the American Journal of Respiratory and Critical Care Medicine.
In the study, Dr. Morgan said, children were separated into four types, based on wheezing and asthma symptoms:
- 425 “never wheezers” - no sign of wheezing or lower respiratory illness from birth to age six.
- 164 “transient early wheezers” - some lower respiratory illness before the age of three, but nothing thereafter.
- 124 “late-onset wheezers” - wheezing at age six, but nothing before.
- And 113 “persistent wheezers” - wheezing and lower respiratory illness before age three and wheezing at age six.
After the researchers followed all the children to age 16, the key finding was that lung function was remarkably stable, according to Fernando D. Martinez, M.D., also of the University of Arizona Health Sciences Center and a co-author.
“There was no significant change in lung function among subjects within either of the three different wheezing groups or the non-wheezing group studied, relative to their peers, from age six to 16 years,” Dr. Martinez said.
The researchers assessed current wheeze via questionnaire, current lung function by spirometry, and atopy by skin prick test. They found:
- The prevalence of atopy and wheeze by age 16 was similar for never and transient wheezers and for persistent and late-onset wheezers.
- Both transient early, and persistent wheezers had significantly lower lung function than did the never wheezers. For example, one-second forced expiratory volume (FEV1) was 75 mL less for the transient wheezers and 87 mL less for the persistent wheezers.
- Late-onset wheezers had lung function similar to that of never wheezers.
“In some respects,” Dr. Morgan said, “the transient wheezers are the lucky ones - they improve rather dramatically from infancy from six years and then they appear flat after that.”
Nonetheless, he said, their lung function is actually low. Whether transient early wheezers are also predisposed to chronic obstructive pulmonary disease is unknown. They would be at risk of causing further damage if, for instance, they start to smoke, he suggested.
While the late-onset wheezers have the same lung function as the never wheezers, he said, they have the same risk of asthmatic symptoms as the persistent wheezers at age 16 - about 50% of both groups reported wheezing during the previous year.
“The late onset wheezers ended up with just as much asthma as the persistent wheezers,” he said. “Asthma delayed is not asthma denied.”
Primary source: American Journal of Respiratory and Critical Care Medicine
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