The correlation between intradermal testing and serum specific IgE to house dust mite in negative skin prick test allergic rhinitis adult patients.

BACKGROUND Diagnosis of allergic rhinitis (AR) is based on history, physical examination, and skin prick test (SPT) while intradermal (ID) test can be performed to confirm the diagnosis in case of negative result of SPT. However, the ID test is not recommended for cat and timothy grass allergy because of its high false positive rate. As a result, the "quantitative" technique of serum specific IgE (sIgE) measurement might be helpful to diagnose AR with more confidence. OBJECTIVES To evaluate the correlation between ID tests and sIgE in the diagnosis of house dust mite (HDM)-sensitive AR patients. METHODS Patients with chronic rhinitis (CR) were recruited and SPT was performed. If SPT was negative, ID test and sIgE to HDM [Dermatophagoides pteronyssinus (Dp)] measurement were performed. RESULTS Eighty-two patients with chronic rhinitis (CR), whose SPTs were negative for Dp, were included. There were 39 males (47.6%) and 43 females (52.4%) aged between 18 and 76 years old (mean age = 43.3 years). The ID test was positive in 13 patients (15.9%), and was negative in 69 patients (84.1 %). sIgE to HDM was positive ( ≥ 0.35 kUA/l) in 2 patients (2.4%). There was a fair to moderate correlation between the size of wheal of ID test and sIgE to HDM (r = 0.44, 95% confidence interval: 0.19 to 0.67, p < 0.01). CONCLUSION ID test has a fair to moderate correlation with sIgE Dermatophagoides pteronyssinus and it can be used in CR patients with negative SPT where sIgE is not feasible.