Sensitization to common allergens
Serum samples were analyzed for total IgE and specific IgE antibodies using the ImmunoCAP® system according to the manufacturer’s guidelines (Phadia AB, Uppsala, Sweden). The tested allergens were as reported elsewhere.13 In this study, we focused on house dust mite (HDM) sensitization (positive = HDM-sIgE >0.34 UA/ml).
Classification ofHDM-sensitized perennial AR in young children
AR is IgE-mediated inflammation of the nasal mucosa. It is diagnosed based on the presence of typical allergic symptoms and nasal eosinophilia, and identification of the causative allergen(s).18,19 AR in children, however, is often undiagnosed, or misdiagnosed because of the multitude of causes for rhinitis.18 Thus, we tentatively classified the phenotypes of the nasal condition in young children in relation to HDM-sensitized perennial AR based on 3 clinical criteria: persistent nasal symptoms, nasal eosinophilia and HDM sensitization. The various combinations of those 3 criteria make up 8 phenotypes, as shown in Table 1. We defined the subtype that was positive for all 3 criteria as ”classical AR”, and the subtypes that were positive for 2 of the 3 criteria as ”eosinophilic rhinitis”, ”AR without nasal eosinophilia” and ”subclinical AR”, respectively. We classified those 4 subtypes as ”AR-like phenotypes” (Table 1). Four subtypes that met only one, or none, of the 3 criteria were classified as ”non-AR phenotypes” (Table 1).