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31-03-2010 | Respiratory | Article

Earlier onset of asthma linked to reduced lung function in children

Abstract

Free abstract

MedWire News: Children who develop asthma before the age of 4 years tend to have poorer lung function than those who develop the disease after this age, study results show.

“It is now generally accepted that a number of distinct phenotypes of childhood asthma exist, and that some of these are more strongly associated with impaired lung function than others,” explain Jenny Hallberg (Karolinska Institute, Stockholm, Sweden) and colleagues.

To investigate whether early-onset asthma is significantly associated with reduced lung function in later childhood, the researchers studied data on 4,089 children in the BAMSE (Children, Allergy, Milieu, Stockholm, Epidemiological Survey) birth cohort.

Questionnaires on doctor-diagnosed asthma, respiratory symptoms, and the current use of asthma medications were completed by parents when their children were aged 1, 2, 4, and 8 years. At the age of 4 and 8 years, 2965 and 2630 children, respectively, underwent lung function tests and allergy assessments.

In total, 406 children (16% of the total cohort) met criteria for a diagnosis of asthma at some point during the first 8 years of life.

Analysis revealed that, on average, children who developed asthma before the age of 4 years (n=202) had significantly poorer lung function at the age of 8 years than those who developed late-onset disease, as indicated by reduced peak expiratory flow (PEF), forced vital capacity (FVC), FEV0.5 , FEV1, FEV1/FVC ratio, and FEV5/FVC ratio measurements.

The association between early-onset asthma and reduced lung function was evident even among children who ceased to experience respiratory symptoms after the age of 4 years, the researchers note in the journal Pediatric Pulmonology.

Children who developed transient asthma before the age of 4 years also had significantly poorer PEF growth between the ages of 4 and 8 years than those who developed late-onset disease.

The researchers also note that allergic sensitization was associated with reduced lung function in children with late-onset asthma, but not in those with early onset disease.

Hallberg and team conclude: “We found that regardless of sensitization status and presence of current symptoms, early age at onset was a predictor of impaired spirometric flows at the age of 8 years.”

They add: “Our main findings emphasize the importance of the first years of life for certain aspects of lung function development, and the lack of effect of sensitization to inhalant allergens on lung function in children with early onset asthma.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Mark Cowen

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