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Background : The Childhood Asthma Management Program study
revealed that 25.7% of children with mild to moderate asthma exhibit a
loss of lung function. The objective was to assess the trajectories of
function by means of serial FEV1 in asthmatic children
participating in out-of-hospital follow-up.
Methods : A total of 295 children (199 boys) who had undergone
at least 10 spirometry tests from the age of 8 were selected from a
single-center open cohort. The annualized rate of change (slope) for
prebronchodilator FEV1 (percent predicted) was estimated
for each participant and three patterns were defined: significantly
positive slope, significantly negative slope, and null slope
(non-significant P-value in the Pearson test). The standard deviation
(SD) of each individual slope was recorded as a variability criterion of
FEV1.
Results : The median (25th and
75th percentile) age at inclusion and the last visit
was 8.5 (8.2, 9.3) and 15.4 (14.8, 16.0) years, respectively. Tracking
of function (null slope) was observed in 68.8% of the children, while
27.8% showed a loss of function (negative slope) and 3.4% showed a
gain in function (positive slope). The children characterized by loss of
function depicted a better initial function and a lower
FEV1 variability during their follow-up than children
with tracking or gain of lung function. At the last visit, these
children were characterized by a lower lung function than children with
tracking or gain of lung function.
Conclusion : Children with a better initial FEV1value and less FEV1 variability are more prone to loss
of lung function.