MEASURING ATOPY IN A MULTICENTER EPIDEMIOLOGIC-STUDY

Skin prick tests are used as a measure of atopy in epidemiological stu dies, but results may be influenced by the fieldworker performing the test. In a multi-centre epidemiological study the method of reporting the results should consider the need for comparability of findings fro m different centres. Data on over 1000 subjects from three English cen tres of the European Community Respiratory Health Survey were analysed to determine whether allergen wheal should be adjusted for histamine wheal, and what cutoff diameter gave the most comparable results. No c onsistent relation between allergen wheal diameter and histamine wheal diameter was found for any fieldworker or allergen. A cutoff of > 0 m m for a positive result gave a more consistent relation with the corre sponding specific IgE value between field-workers than either a cutoff of greater than or equal to 3 mm or the use of the mean wheal diamete r. While this result is not immediately generalisable to studies using different skin prick test reagents, the method of analysis to determi ne the appropriate criterion of reporting can be used in other epidemi ological studies.