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 (IT3) or 5 yr of treatment (IT5). 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 (IT3: 41) or 5 yr (IT5: 40) of immunotherapy. After 3 years, rhinitis global scores decreased in IT3 (44%; p = 0.002) and in IT5 (50%; p = 0.001). Asthma global, symptom and medication scores decreased by 100% in IT3 (p = 0.001) and IT5 (p = 0.001). VAS scores also diminished significantly (IT3: 70%, p = 0.001; IT5: 62.5%; p = 0.001). At 5th year, global rhinitis scores were reduced an additional 30% in IT5 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 IT3 children (p = 0.705) developed new sensitizations. At 5th year, sIgG4 determinations decreased in IT3 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.