The use of standardized extracts in allergen immunotherapy

Background: Double-blind, placebo-controlled studies have established that injection allergen immunotherapy is clinically effective. However, it is no t known to what extent the doses of allergen extract commonly used in clini cal practice match those that have been used in these controlled studies. Objective: The aim of this study was to determine by questionnaire the dose s of standardized allergen extracts commonly used by board-certified allerg ists in the United States and to compare these with doses that have proven effective in double-blind, placebo-controlled studies. Methods: A questionnaire containing a hypothetical case and asking for a re commended allergen prescription for maintenance immunotherapy was mailed to 500 randomly selected board-certified members of the American Academy of A llergy, Asthma and Immunology living in the United States. The recommended doses were compared with those doses of the extracts that had been proven e ffective by using major allergen content figures for representative standar dized US allergen extracts provided by an allergy extract laboratory. Results: Responses were received from 118 (23%) of the addressees. Eighty ( 16%) contained interpretable data on maintenance dosing for extracts. The m edian doses of pollen recommended were comparable with those that have been demonstrated to be clinically effective. Median doses of house dust mites were only slightly Lower than those that have proven effective. Median dose s of animal dander, on the other hand, were well below those used effective ly in controlled studies. Although the median doses used were often in the range of proven doses, the range of doses recommended by allergists include d some that were one tenth to one five hundredth those of the median doses. Conclusion: In the absence of useful guidance from the federal regulatory a uthorities, American allergists, for the most part, use doses of pollens an d house dust mites that are within the proven range. Their dosing of animal dander is generally below proven effective doses. There is, however, a wid e range of dosing of all extracts used, and there is use of mixes that have no botanical basis. Therefore there is need For studies defining what are effective and ineffective allergen extract doses.