Introduction
As reported by Martinez,1 approximately 40% of the
deficits in maximal expiratory flow observed at 6 to 7 years of age in
children with asthma were present at birth, whereas 60% of the deficits
develop during the preschool years.2 A further decline
in FEV1 occurs during the school years as part of the
natural history of asthma.3 Only one study has
demonstrated that asthmatic children can exhibit a loss of lung function
during childhood based on spirometry.4 In this study,
a reduction in postbronchodilator FEV1% predicted was
observed in 25.7% of children with mild to moderate asthma who were
enrolled in the Childhood Asthma Management Program
(CAMP).4 Factors associated with a reduction in
postbronchodilator FEV1% predicted included a younger
age at enrollment, male sex, study site and higher postbronchodilator
FEV1% predicted at baseline. As a consequence, the
results of Covar and colleagues should be confirmed (1) using a more
common asthma definition criteria, as hyperresponsiveness to
methacholine was an inclusion criterion in their
study,4 and (2) in an out-of-hospital series of
children that is more representative of childhood asthma than a cohort
included in a therapeutic trial involving children with mild to moderate
persistent asthma.
The objective of our prospective observational study was to assess
whether an abnormal decline in the trajectory of lung function by means
of serial FEV1 monitoring can be identified in asthmatic
children participating in out-of-hospital follow-up.