The predictive value of the acute effect of beclomethasone-dipropionate on an exercise-challenge test for the outcome of longterm treatment with beclomethasone-dipropionate in childhood asthma.

Asthma is a heterogeneous disease and clinical phenotypes are highly variable.
This is exemplified in the variability of patients*
responses to medications such as Qvar. It is a critical clinical question
whether a particular therapy will be effective in
an individual child with symptoms of asthma. At the moment, there is a lack of
diagnostic tools to assess this individual
responsiveness.
Qvar is an inhaled corticosteroid (ICS) used as controller therapy in children
with asthma, providing protection
against bronchial hyperresponsiveness (BHR) and exercise induced
bronchoconstriction (EIB). A single dose of an ICS can have a significant
effect on BHR measured by a bronchial provocation test (BPT). This rapid
response shows variability similar to the
variable responsiveness to long term treatment. We hypothesized that the effect
of a single dose of Qvar on a BPT (an exercise-challenge test) could predict
the effect of longterm therapy with Qvar on BHR.

This study aims to investigate if there is a correlation between the severity
of bronchoconstriction after an exercise challenge test 6h after a single dose
of Qvar and after 4 weeks of treatment with Qvar, in order to know if the
respons to a single dose of Qvar can predict individual response on the longer
term.What

This study is of a prospective, open-label design.

All children are treated with Qvar 100µg twice daily for 4 weeks.

This study is conducted in children because the burden of EIB is large in
childhood and there are substantial differences in the
pathofysiology of EIB between adults and children. Children more often perform
spontaneous exercise and therefore do not always use prophylactic inhalation
therapy.
Prophylactic maintenance therapy is therefore more widely used in children than
in adults. We expect treatment with Qvar will improve pulmonary function,
decrease symptom scores and diminish bronchial hyperresponsiveness. Side
effects of Qvar are usually mild. Children will fill in an Asthma Control Test
and will perform 2 exercise challenge tests. An exercise challenge test can
cause dyspnea, for which Salbutamol will be given. The amount of dyspnea is
comparable with the dyspnea that children experience during daily exercise. In
general, children don't experience the exercise challenge tests as strenuous.