Controlling Indoor Mite Exposure: The Relevance of the Acarex Test

Abstract

The Acarex test is an easy, rapid and cost-effective means of assessing exposure to house dust mites. The present study was designed to evaluate the correlation between the Acarex test using a 4-point and a 7-point scale and the major allergens content (Der p1 + Der f1 ) of house dust samples measured by an ELISA technique and also to assess the validity of the test with regard to both sampling and reading of the colour scale. Some 719 house dust samples from patients' homes were evaluat ed using the supplied 4-point scale (classes 0, 1, 2, 3) and again with interpolation of 3 intermediate scale points (classes 0.5, 1.5, 2.5) and Der p1 + Der f1 content using ELISA. Reliability of sampling was studied in 39 dwell ings comparing results obtained by householders and technicians. Reproducibility of reading the colorimetric scale was evaluated in 3 trained technicians and 15 untrained people. The correlation between the Acarex and the ELISA results was 0.68 (p < 0.0001) with class 0 reliable for assessing low allergen levels, class 1 unable to discriminate, and classes 2 and 3 reflecting high aller gen levels (class 3 identified 94.2% of samples with an allergen content greater than 10 μg.g-1). Discrepancies between Acarex scores for samples collected by patients and those collected by technicians did not exceed half a scale point. Reproducibility of reading by trained techni cians gave intraindividual and interindividual coeffi cients of variation of 0% for classes 0 and 3 and about 20% or more for the other classes. On average readings by untrained participants had 42% discrepancies, mostly in classes 1 and 2. We conclude that the Acarex test is a useful home test whether used by patients or techni cians ; misclassifications of colour readings were less fre quent at the scale extremes. Copyright©2001 S. KargerAG, Basel