Reevaluation of the Acarex test ten years later.

The Acarex test (a semi-quantitative guanine test) is the only home test th at has been available for the past ten years to identify house dust mite ex posure. A significant correlation between the four classes in the Acarex te st and the Der p1 + Der fl content has previously been shown. The aim of th is study was to reevaluate the above correlation in a larger number of samp les and to assess the practical aspects of this test. In order to improve a ccuracy of the results, three intermediate classes were included (0.5 1.5, 2.5) in addition to the the four standard classes. Seven hundred and ninete en house dust samples collected from patients' homes were evaluated by the Acarex test and ELISA (Der p1 + Der fl). The correlation between Acarex tes t results and major allergen content was 0.68 (P < 0.001). It was observed that a significant increase in Der pi + Der fl content was correlated with an increase in class scale (i.e., for class 0: 1.4 <mu>g/g; and for class 3 : 125.73 mug/g (P < 0.001)). The percentage of samples with <greater than o r equal to> 2 mug Der p1 + Der 11 content and those with a Der p1 + Der fl content of greater than or equal to 10 mug were respectively 77 and 54.9%. Samples containing > 2 mug mite allergens were defected in class I with 86. 7% sensitivity and 78.2% specificity. Samples containing, 10 mug mite aller gens were detected in class 2 with 63% sensitivity and 88% specificity. The reliability of patient sampling and the reproducibility of the Acarex colo rimetric reaction reading were also assessed. Discrepancies between the Aca rex scores for the samples collected by the patients and those collected by the technicians did not exceed half a class. Regarding the reproducibility of the reading of the colorimetric scale, misclassifications were found in the results of both trained technicians and untrained participants, especi ally for class I and 2 However, the significance of these discrepancies was negligible. It was concluded that patient sampling can be as reliable as t echnician sampling in assessing exposure to house dust mites, and that the possible misreading of the Acarex test does not affect patient management a nd care, in conclusion, the Acarex test remains an easy, rapid and cost-eff ective means of assessing exposure to house dust mites. (C) 2000 Editions s cientifiques et medicales Elsevier SAS.