Problem of nonresponse to allergen immunotherapy

Introduction
Allergen immunotherapy (AIT) is very important and effective and reduces medication use in patients with allergic rhinitis. However, some patients have no response to AIT.

Aim
To explore the problem of nonresponding patients after AIT.

Material and methods
This retrospective randomized observational study included 1056 patients with allergic rhinitis who underwent subcutaneous injection allergen immunotherapy (SCIT). Patients who received SCIT to one of the following allergens: grass pollen, birch, trees, mugwort, house dust mites, Alternaria or cat were analyzed according to the inclusion criterion of ≥ 20% improvement in all monitored parameters. There were symptoms and medication score, rhinitis symptom score and serum allergen-specific IgE and IgG4.

Results
A total of 806 (76.3%) patients met the criterion of 20% or greater improvement after SCIT. The greatest effectiveness was obtained in patients receiving SCIT to grass pollen (293 participants; 83.2%), birch (82; 81.2%) and house dust mites (255; 76.4%). Statistically significant predictors of an improved AIT outcome in the multivariate analysis were SCIT to grass pollen (OR = 2.34, p = 0.035), SCIT to birch (OR = 2.25, p = 0.021) and the presence of only intermittent allergic rhinitis before SCIT (OR = 2.05, p = 0.039). Patients who received SCIT to mugwort, Alternaria or cat had weak response results especially in long-term observations.

Conclusions
The best predictors to obtain good responsiveness to SCIT are the presence of intermittent allergic rhinitis to grass or birch pollen. Patients with allergies to mugwort, Alternaria and cat with a prolonged duration of persistent allergic rhinitis dominated in the group of nonresponders to SCIT.