DISCUSSION:
In this retrospective, data-base
study we found that the use of major-allergen analysis improves the
diagnosis of pollen allergy and helps recommending for or against AIT.
The added value of MD was
especially important in patients allergic to tree pollen or weed pollen
as the differentiation between birch/ash-tree or mugwort/ragweed was not
easily discernable without MD due to overlapping pollen seasons of these
plants in Austria. Interestingly, in patients only sensitized to grass,
birch or ash-tree, the agreement of IgE-reactivity to extract and major
allergen was very high (83-94%), whereas it was lower for mugwort or
ragweed (64%, 74%). Hence, it can be assumed that in single-sensitized
grass- or tree pollen patients either the extract or the major allergens
can be used interchangeably. This does not hold true for weed-sensitized
patients or patients double-sensitized to birch and ash-tree or mugwort
and ragweed.
Sastre et al14 investigated if MD (using a
micro-array-based panel including pollen-allergens) rather than results
of SPT had an influence on the AIT decision in 141 patients with
allergic rhinoconjunctivitis and/or asthma living in Spain. They found
that including MD changed the AIT decision in 46% of the patients. As
the pollen season is different in Spain compared to Austria with mainly
cypress, plane, olive and grass-pollen being prevalent in the Spanish
study region, the data cannot be directly compared to our observation.
However, we found in our study similar results as 50% of patients with
positive ash-tree extract, and negative Ole e 1 was prescribed birch-AIT
(as they were Bet v 1 positive), and 41.3% of mugwort/ragweed
double-sensitized patients were prescribed ragweed-AIT because of
MD-results. An Italian study in 651 children found comparable
results.15 In 47% of pollen-allergic patients MD led
to a change of AIT-recommendations. The pollen season in Italy is more
comparable to Spain than to Austria but the principle is the same.
A more recent German study found no improvement by including MD in
weed-allergic patients.16 However they included only
mugwort and English plantain in their IgE-profiles without looking at
ragweed which is more relevant in Eastern-Austria than in the described
German region.10, 17
The relevance of the present study is that it included a large number of
patients (>4000) from the database of an allergy-center
with a wide age group from toddlers to the elderly in eastern Austria.
The number of double-sensitized patients with parallel extract and MD
measurements provides a good basis for the analyses performed. We could
also review the patients´ charts if additional clinical information
(such as the doctor´s decision for or against AIT) was necessary.