House-dust mite nasal provocation: a diagnostic tool in perennial rhinitis

In perennial allergic rhinitis (PAR), the skin-prick test (SPT) is a good diagnostic tool to identify the specific allergens. A nasal provocation test (NPT) is used to identify allergens and to confirm the diagnosis. The aim of this study was to determine the optimal cutoff values of symptom and peak nasal inspiratory flow (PNIF) changes after dust-mite NPT for predicting PAR. We also studied the relationship of the changes of symptoms in NPT and the wheal size of SPT.

One hundred five patients with perennial rhinitis underwent the NPT to Dermatophagoides pteronyssinus and the SPT. The NPT was assessed by changes in symptoms and PNIF. The optimal cutoff values of the symptoms score and PNIF changes after the NPT for predicting the SPT were determined using a receiver operating characteristic (ROC) curve. The relationship of the wheal sizes of SPT and the changes from the NPT were analyzed.

Forty-eight patients had a positive SPT to D. pteronyssinus, of whom 33 patients had a positive NPT by increases of the symptom score. Twenty patients had a positive NPT by decreases of PNIF. The area under the ROC curve was 0.85 for symptom score changes and it was 0.612 for PNIF changes. There was a significant correlation between the wheal size of the SPT and symptom changes in the NPT.

Nasal provocation is a valuable test to confirm the diagnosis of D. pteronyssinus allergy, especially when the wheal from the SPT is small. The symptom change after the house-dust mite NPT is better than the PNIF change for predicting the PAR.