Background: Allergen immunotherapy (AIT) has proven to be effective. However, no biomarkers capable of predicting the clinical response to AIT have been detected. The aim of the present study was to determine a cutoff value for serum specific IgE that could be associated with effective AIT.

Methods: We evaluated 174 allergic patients (83 males) with ages ranging between 6 and 77 years. All patients were monsensitized and received sublingual immunotherapy (SLIT) for at least 3 years with a single allergen extract. Symptom severity was assessed using the visual analog scale (VAS). Drug use was also evaluated. A responder was defined as a patient whose VAS score fell by at least 30% over baseline.

Results: The response to SLIT was considered effective in 145 patients (83.3%). The use of allergen-specific IgE levels >9.74 kUA/L as a biomarker of effective SLIT yielded a sensitivity value of 96.4%, specificity of 100%, and an area under the receiver operator characteristic curve of 0.987.

Conclusions: Assessment of serum specific-IgE before AIT could be a useful biomarker for predicting response to AIT.

Key words: Allergen-specific immunotherapy. Serum specific IgE. Responder.