[Long-term efficacy of Dermatophagoides pteronyssinus immunotherapy in patients with allergic rhinitis: a 3-year prospective study].

Objective: To evaluate the long-term efficacy of subcutaneous immunotherapy with Dermatophagoides pteronyssinus (DerP) in patients with allergic rhinitis.

Methods: Ninety-two patients with allergic rhinitis to DerP were randomly allocated to receive either specific immunotherapy (n = 46) or medical treatment (n = 46). Symptom and medication scores and skin response to Derp were assessed to evaluate the clinical efficacy in the baseline and after three years treatment. DerP-specific IgE and IgG4 were measured.

Results: After three years treatment, the immunotherapy group showed sustained reductions in symptom scores (before treatment 9.20 [7.50;11.13], after treatment 3.32 [2.49;5.12], Z = -5.13, P < 0.05), medication scores (before treatment 0.72 [0.47;0.83], after treatment 0.31 [0.28;0.45], Z = -5.78, P < 0.05) and specific skin response to Derp (t = 6.37, P < 0.05) when compared with control group. There were no differences in the level of serum specific IgE before and after three-year treatment (before treatment 16.32 [4.34;38.65] kU/L, after treatment 15.85 [4.93;46.27] kU/L, Z = -0.84, P > 0.05), but the level of serum specific IgG4 increased significantly after one year treatment in immunotherapy group (before treatment 486 [319;1439] AU/L, after treatment 8387 [7732;16 634] AU/L, Z = -2.81, P < 0.05). After three-year treatment, 7.5% (3/40) of patients had asthma in immunotherapy group compared to 27.8% (10/36) in the control group (χ(2) = 5.50, P < 0.05), and 15.0% of the initially DerP nonsensitized patients in immunotherapy group had developed new sensitization compared to 47.2% in the control group (χ(2) = 9.32, P < 0.05).

Conclusion: Three years immunotherapy improves allergic rhinitis symptoms, increases the level of serum specific IgG4, reduces the development of asthma and new sensitization.