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.