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.