Proficiency testing of allergen measurements in residential dust.

BACKGROUND: Analyses of household dust for allergens are more common with increased efforts to reduce and control asthma. Currently, no laboratory accreditation or quality assurance program specific to household dust allergen analyses exists. Moreover, there is an absence of peer-reviewed data on within-laboratory and between-laboratory variability that is achievable for these analyses. OBJECTIVES: The purpose of this study was to characterize the levels of intralaboratory and interlaboratory variability in analyses of allergen concentrations in residential dust and to investigate the utility of quality control samples for monitoring laboratory performance. METHODS: Aliquots from homogeneous batches of dust and dust extracts were provided to 8 commercial, academic, and municipal laboratories to be analyzed for as many as 6 allergens (Der p 1, Der f 1, Fel d 1, Can f 1, Bla g 1, Mus m 1) by using ELISA techniques. RESULTS: Coefficients of variation on the estimated geometric means from the analytical results ranged between 61% and 93%. In most cases, between-laboratory variability was the dominant component of total variability. In spite of this between-laboratory variability, reasonable agreement was observed between the means of allergen levels in the reference laboratory characterizations and the estimated geometric means from the model fitting of results across participating laboratories. CONCLUSION: The results from this study indicate that, in most cases, participating laboratories could measure the concentrations of allergens by using ELISA procedures with a level of accuracy and precision that may be acceptable in many situations.