Guideline recommendations on the use of allergen immunotherapy in house dust mite allergy: Time for a change?

Guidelines on the treatment of asthma, allergic rhinitis (AR), and allergen immunotherapy (AIT) lack recommendations for house dust mite (HDM) allergy. An expert panel reviewed current guidelines in the light of new data to assess whether guidelines could be improved. Most guidelines and key position papers did not provide specific recommendations on treatment of allergic asthma (AA) caused by HDM allergy, although some included AIT as a treatment option for AA in general. Around half of the guidelines stated that AIT with HDM extract was an effective treatment for AR, with several indicating sublingual immunotherapy as an option. This heterogeneity is caused by quality issues affecting studies of AIT with perennial allergens in patients with AA and AR, including use of different diagnosis and severity criteria, lack of consistent scoring or grading systems for primary and safety outcomes, and lack of consensus on treatment parameters. There is a need for well-designed clinical trials to serve as a basis for guideline recommendations. Although results from recent studies strengthen the evidence base for the efficacy and safety of sublingual immunotherapy in patients with HDM-induced AA and AR, their effect on subsequent guideline updates will depend on the methodology and evidence model used by each guideline.