Context: Although subcutaneous allergen immunotherapy (SCIT) is effective in allergic rhinitis (AR) and asthma, it carries a risk of local and systemic adverse reactions.
Objective: The aim of this study was to evaluate the rates and clinical characteristics of local and systemic reactions (LR and SR), and to identify their relation of demographic features, allergen extracts and diagnosis.
Materials and methods: This study analyzed the administration of SCIT from 1983 to 2013; involving 1816 patients affected by allergic asthma and/or AR.
Results: The rates of SR from SCIT were 0.078% per injection and 9% per patient. According to the World Allergy Organization 2010 grading system, 91 grade 1 reactions (44%), 67 grade 2 reactions (32.3%), 33 grade 3 reactions (16%) and 16 grade 4 reactions (7.7%) were seen. There was no fatal outcome from any of the SRs. Risk factors for a SR included: aluminium-adsorbed extract, pollen-containing vaccines, large LR and recurrent (≥2) LRs. The total LR rates were 0.062% per injection and 5.2% per patient; the small LR rates were 0.027% per injection and 2.3% per patient, and the large LR rate were 0.035% per injection and 2.9% per patient. Female gender, depot extracts, calcium phosphate-adsorbed extract and pollen vaccines were identified as risk factors for LR.
Conclusion: The analysis of our data over a 30-year period confirmed that SCIT with inhalant allergens conducted strictly according to the standard protocols and when administrated by experienced staff is a safe method of treatment with only a few side-effects.
Keywords: Inhalant allergens; local reaction; risk factors; subcutaneous allergen immunotherapy; systemic reaction.