Association of allergy, atopic history and eosinophilia with
AHR
Several studies have identified a personal history of having an allergy
to various antigens as a risk factor for AHR(3, 12-14). Tree pollen,
especially, has been described as an important allergen in this
context(15), while no association could be verified in relation to mold
sensitization(15, 16). In accordance with previous studies, we found an
association of AHR with general skin test positivity as well as with
sensitization to most aeroallergens, except mold, and where tree pollen
sensitization reached the highest significance level. This high
significance might be due to the specific local environment. The birch
tree is widely spread in Germany and has emerged as a common allergen in
children with allergic rhinitis and asthma(17).
In contrast, in an earlier study including children who were also
without an obstructive pattern, no significant relationship between
personal allergy and the presence of AHR was detectable(7). However,
unlike the earlier study, in the present study patients with
predominantly exercise-induced symptoms were excluded. The symptoms of
the patients in our study group occurred mainly when they were at rest
and were frequently triggered by allergens. Thus, it can be assumed that
in the present study there are more patients with allergies, supported
by the higher percentage of sensitized children compared with the
previous study (51.2% vs 43.6%). Correspondingly, a stronger
association between allergy and AHR can be expected. Especially in
atopic patients, the MCC is accepted as a highly sensitive tool to
detect AHR(18).
A family history of atopy has also been described by some authors as
associated with AHR(19, 20), while others could not confirm such a
relationship(21). Although our data did not show a significant
relationship of atopic family history with AHR, co-existence of two or
more atopic diseases in the family nearly reached significance. In
general, it is difficult to evaluate the influence of a genetic history
because subjective measures might lead to overestimating the risk from
family history. So it can be assumed that parents suffering from
respiratory symptoms would be more likely to recognize symptoms in their
children and consult a physician(21, 22).
In accordance with the results of previous studies, we identified an
association between high eosinophilia counts and AHR(7, 14, 23).
Unfortunately, our database of eosinophilia was incomplete, therefore it
was not included in the multivariate analysis.