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Reduced lung function both before bronchiolitis and at 11 years
S W Turner1, S Young, L I Landau
1University Department of Paediatrics, Princess Margaret Hospital for Children, Perth, Australia. s.w.turner@ncl.ac.uk
Insights
Bronchiolitis in infancy is linked to reduced lung function (V'maxFRC) and increased wheezing in childhood. However, this lung function deficit appears to stem from pre-existing conditions rather than the illness itself.
Area of Science:
- Pediatric Respiratory Medicine
- Pulmonology
- Epidemiology
Background:
- Previous research indicated a link between reduced maximal expiratory flow at functional residual capacity (V'maxFRC) and bronchiolitis.
- A hypothesis was formed that bronchiolitis would lead to diminished lung function and heightened respiratory symptoms in children.
Purpose of the Study:
- To investigate the long-term effects of bronchiolitis on childhood lung function and respiratory symptoms.
- To determine if bronchiolitis causes persistent lung function deficits or exacerbates pre-existing conditions.
Main Methods:
- Maximal expiratory flow at functional residual capacity (V'maxFRC) was measured at one month of age.
- Children diagnosed with bronchiolitis were prospectively identified and followed.
- Annual respiratory symptom questionnaires were administered from ages 3 to 6.
- A comprehensive assessment at 11 years included questionnaires, lung function tests, airway responsiveness to histamine (AR), and skin prick testing.
Main Results:
- Children with a history of bronchiolitis exhibited increased viral-induced wheeze at ages 3 and 5.
- At 11 years, individuals with prior bronchiolitis showed reduced mean z scores for % V'maxFRC and % FEF(25-75) compared to controls.
- No significant differences were observed between groups at age 11 for FEV(1), FVC, PEF, AR, atopy, wheeze, or diagnosed asthma.
Conclusions:
- Reduced lung function is evident both before and after bronchiolitis, with comparable levels of deficit.
- The findings suggest that the wheeze and reduced lung function observed post-bronchiolitis are primarily attributable to premorbid lung function rather than the infection itself.
Background And Aims:
We have previously shown an association between reduced premorbid lung function (V'maxFRC) and bronchiolitis. We hypothesised that individuals with bronchiolitis will go on to have reduced lung function and increased respiratory symptoms in childhood.
Methods:
V'maxFRC was measured at 1 month of age; individuals with bronchiolitis were prospectively identified. Annual symptom questionnaires were completed from 3 to 6 years. At 11 years of age, children underwent an assessment including questionnaire, lung function, airway response to histamine (AR), and skin prick testing.
Results:
Eighteen individuals with bronchiolitis were ascertained from 253 cohort members. Children with bronchiolitis had increased viral induced wheeze at 3 (OR 5.8, 95% CI 1.4 to 25.2; n = 103) and 5 years (OR 5.3, 95% CI 1.1 to 25.5; n = 101). At 11 years of age, 194 children were assessed including 16 with past bronchiolitis. These 16 individuals had reduced mean z scores for % V'maxFRC compared with other children (-0.56 and 0.06 respectively) and mean z scores for % FEF(25-75) at 11 years (-0.53 and 0.06 respectively). At 11 years, FEV(1), FVC PEF, AR, atopy, wheeze, and diagnosed asthma were not different between groups.
Conclusions:
Reduced lung function is present before and after bronchiolitis; the level of reduction is comparable. The mechanism for wheeze and reduced lung function after bronchiolitis appears to be related to premorbid lung function and not bronchiolitis per se.