House dust mite subcutaneous immunotherapy has sustained long-term effectiveness on allergic rhinitis and asthma: A 10-year follow-up

Background: Maintenance doses for allergen immunotherapy (AIT) have been recommended for at least 3 years but little data on long-term efficacy is available depending on AIT duration. To show sustained efficacy 10 years after completion of treatment with depigmented-polymerized house dust mite (dpg-pol HDM) allergen extract in adults with asthma and/or rhinoconjunctivitis.Methods: Patients included in a double-blind placebo-controlled AIT study with dpg-pol HDM allergen extract were reviewed at completion of the perennial treatment and 10-year follow-up (10y-FU). Change in symptom and rescue medication score was the primary objective. Visual analog scale (VAS), asthma control test (ACT), and degree of disease control were the secondary objectives. A comparative analysis between patients who underwent AIT treatment for <3 years and >= 3 years was performed.Results: Data from 31 patients (mean age 38 years) were available at 10y-FU. All had asthma and 29 had rhinoconjunctivitis at baseline. Twenty-three patients were treated >= 3 years and 8 for <3 years. Seventeen (55%) patients were asymptomatic at completion of AIT, with significant differences for nasal, conjunctival, and bronchial symptoms (p < .0001) compared with baseline only in those patients treated >= 3 years. Nine (52.9%) patients remained completely asymptomatic at 10y-FU, all were treated for >= 3 years. Moreover, significant reduction in the number of patients with rhinitis (p = .0117), conjunctivitis (p < .0001), and bronchial (p = .0005) symptoms was observed at 10y-FU compared with baseline only in the >= 3 years treated. Ten (32.3%) patients did not require any rescue medication at 10y-FU, all had been treated for >= 3 years. ACT at 10y-FU showed a good control of asthma (median 23.5; 95% IC[22.0, 25.0]). No significant differences were observed between VAS at end of treatment compared with VAS at 10y-FU.Conclusions: Sustained clinical efficacy is achieved 10 years after completion of depigmented-polymerized HDM, however, these findings were observed only if patients are treated for at least 3 years.