Double-blind and placebo-controlled study to assess efficacy and safety of a modified allergen extract of Dermatophagoides pteronyssinus in allergic asthma

Background:  A randomized double-blind, placebo-controlled study was conducted in patients allergic asthma sensitized to Dermatophagoides pteronyssinus. Objective:  To evaluate the efficacy and safety after 1-year of immunotherapy with a modified D. pteronyssinus extract compared with placebo. Material and methods:  Fifty-five patients were randomly allocated to receive the active treatment (n = 29), or placebo (n = 26). The main outcome was the specific bronchial provocation test (BPT). Other parameters analysed were dose–response skin prick test (SPT), symptom and medication scores and asthma quality of life (AQLQ). Results:  At the end of the study, the active group showed a significant increase in the PD20FEV1 compared with placebo (P = 0.0029). Nineteen patients of the active vs 10 of the placebo group needed more than twice the initial amount of allergen extract to have a positive BPT (P = 0.0293); seven patients in the placebo vs one in the active group needed less than half (P = 0.0137). In SPT, a significant improvement (P = 0.0049) was found in the active group. This group also had a median reduction of 91.5% in symptom scores, whereas the placebo group increased by 86%. Medication scores decreased in both groups (56% in the active and 11.4% in the placebo). In AQLQ, the differences between both groups were significant (P = 0.0234) at the end of the study. Conclusion:  After 1 year of treatment, the modified extract of D. pteronyssinus demonstrated to be safe and efficacious to treat patients with asthma and allergic rhinoconjunctivitis sensitized to this mite.