Safety of specific immunotherapy using a depigmented and polymerised extract of Dermatophagoides pteronyssinus in children under five years of age.

BACKGROUND Different opinion documents point to a patient age of under five years as a relative contraindication to specific immunotherapy, arguing that this age group has a greater risk of developing anaphylaxis, and that specially trained personnel are needed to deal with the problem if it occurs. However, insufficient evidence exists to support such an affirmation. PATIENTS AND METHODS A retrospective follow-up observational study was made of patients aged 60 months or younger who had been subjected to specific immunotherapy. We included 77 children with a diagnosis of extrinsic bronchial asthma (n=68), extrinsic spasmodic cough (n=5) and allergic rhinitis (n=4) confirmed by clinical criteria and prick-test, with specific IgE positivity to Dermatophagoides pteronyssinus. All patients received specific immunotherapy with an extract of depigmented D. pteronyssinus polymerised with glutaraldehyde, involving an initial cluster protocol of two weeks and monthly maintenance doses. All observed adverse reactions were recorded, and classified according to European Academy of Allergy and Clinical Immunology (EAACI) criteria. RESULTS A total of 1837 doses were administered to the 77 patients, with four adverse reactions being observed in three patients. Three reactions (0.16% of the administered doses) were local and immediate, while one was systemic and of grade 2 (0.05% of the administered doses) - consisting of an episode of nocturnal wheezing. CONCLUSIONS Specific immunotherapy in children under five years of age with the extract used is safe. We consider that further studies are needed, involving other types of extracts, to allow reconsideration of the relative contraindication of patient age for the administration of immunotherapy.