House Dust Mite and Grass Pollen Allergen Extracts for Seasonal Allergic Rhinitis Treatment: A Systematic Review

Background: The treatment of allergic rhinitis is important due to the burden that the disease causes globally. The objective of this review is to explore the efficiency of house dust mite and grass pollen extracts in allergic rhinitis treatment. Methods: We performed research in electronic databases and searched relevant articles on PubMed, CINAHL, OVID, ScienceDirect, Cochrane CENTRAL, and MEDLINE. We used keywords such as ‘allergic rhinitis', ‘sublingual immunotherapy’, ‘randomized controlled trials', ‘grass pollen’, 'allergen immunotherapy’, and ‘house dust mite’. We included nine randomized controlled trials (RCTs). Quality assessment of included studies was performed independently by two authors. Results: We included nine eligible RCTs in this review. Five RCTs were about grass pollen extracts and four RCTs were about house dust mite extracts. Most of the studies reported positive results and suggested further evaluation of sublingual immunotherapy (SLIT) treatment. Grass pollen extracts mostly used were Dactylis glomerata, Poa pratensis, Lolium perenne, Anthoxanthum odoratum, Phleum pratense, and Parietaria. House dust mite extracts used were from Dermatophagoides pteronyssinus and Dermatophagoides farina. According to the quality assessment, no bias was observed in the included studies. Conclusions: Although sublingual allergen immunotherapy shows a benefit compared to placebo in the treatment of allergic rhinitis and rhino-conjunctivitis in adults, the results are interpreted with caution due to the high heterogenicity among studies in treatment protocols and dosing. More standardization among studies is needed.