Optimal duration of allergen immunotherapy in children with dust mite respiratory allergy

Background Subcutaneous immunotherapy ( SCIT ) discontinuation data in children remain scarce. Objective We sought for differences in the clinical efficacy of 3 vs. 5 yr of SCIT in children with dust mite respiratory allergy. Methods We performed a 5‐yr, phase IV prospective study. After the first year, the patients were randomized to 3 ( IT 3) or 5 yr of treatment ( IT 5). Efficacy was assessed at 3rd and 5th year by symptom and medication scores and visual analog scales ( VAS ). Skin tests with common allergens and in vitro assessments were also performed. Results Eighty‐one children (mean age: 9 yr) were randomly assigned to 3 ( IT 3: 41) or 5 yr ( IT 5: 40) of immunotherapy. After 3 years, rhinitis global scores decreased in IT 3 (44%; p = 0.002) and in IT 5 (50%; p = 0.001). Asthma global, symptom and medication scores decreased by 100% in IT 3 (p = 0.001) and IT 5 (p = 0.001). VAS scores also diminished significantly ( IT 3: 70%, p = 0.001; IT 5: 62.5%; p = 0.001). At 5th year, global rhinitis scores were reduced an additional 30% in IT 5 children. Comparisons between both groups did not show differences in rhinitis (p = 0.055), asthma global scores (p = 0.948) or VAS scores at 5th year. Twenty percent of IT5 (p = 0.002) and 7% of IT 3 children (p = 0.705) developed new sensitizations. At 5th year, s I g G 4 determinations decreased in IT 3 without significant variations in IT5. Conclusions Three years of SCIT induced significant improvement in children with dust mite respiratory allergy, but a 5‐yr course added clinical improvement in rhinitis.