House dust mites have a well-established causal role in patients with persistent allergic respiratory diseases, such as allergic rhinitis (AR) and allergic asthma (AA). These atopic diseases lead to increased burden of disease and health care costs, particularly in patients with uncontrolled or poorly controlled disease.
Because effective allergen avoidance is not always possible in a domestic setting house dust mites-induced respiratory diseases are treated with a range of symptomatic medications or with allergen immunotherapy based on purified extracts of house dust mites bodies, feces, or both. The efficacy of allergy immunotherapy in patients with allergic respiratory conditions has long been acknowledged by national and international guidelines. A meta-analysis of double-blind, placebo-controlled (DBPC) randomized clinical trials (RCTs) of subcutaneous allergen immunotherapy (SCIT) in adults and children with AA (including asthma induced by allergens other than house dust mites) has shown that this treatment is effective in relieving symptoms, decreasing rescue medication use, and improving bronchial hyperresponsiveness.
In a double-blind, placebo-controlled study of mite-sensitive children, most children who received placebo treatment after one year of active treatment relapsed within months, whereas those in the active treatment group had a persistent effect of immunotherapy. With immunotherapy with a standardized house dust mite vaccine administered for one to up to 6 years, it was found that immunotherapy was more effective after it was discontinued if it had been administered for at least 3 years.
Recent meta-analyses and reviews suggest that sublingual allergen immunotherapy (SLIT) with HDM extracts might be beneficial in patients with AA, although the effect size reported is small to moderate and varies greatly from one study to another.
Calderon M A et al. An evidence-based analysis of house dust mite allergen immunotherapy: a call for more rigorous clinical studies[J]. Journal of Allergy and Clinical Immunology, 2013, 132(6): 1322-1336.
Bousquet J et al. Allergen immunotherapy: therapeutic vaccines for allergic diseases[J]. Annals of allergy, asthma & immunology, 1998, 81(5): 401-405.