Risk factors for adverse systemic reactions occurring during immunotherapy with standardized Dermatophagoides farinae extracts.

The most serious problem in practical immunotherapy is the risk of occasional, potentially life-threatening adverse systemic reactions. Elucidation of the incidence of, and possible risk factors for, systemic reactions would have a profound effect on the decision about how to manage allergic rhinitis. The aim of this retrospective study was to document the incidence and risk factors of adverse systemic reactions during immunotherapy using standardized Dermatophagoides farinae (D. farinae) extracts for perennial allergic rhinitis. This study included 386 patients (22,722 injections) with perennial allergic rhinitis who had received immunotherapy with standardized D. farinae extracts in our clinics for the past 5 years. The incidence of systemic reactions was 6.22% per patient and 0.12% per injection. The time of onset of systemic reactions ranged from 3 to 30 min (mean 11.3 min) after injections. Our study has demonstrated that asthma, atopic dermatitis and a high level of IgE in serum, but not a high level of specific IgE in serum, are important high risk factors that may induce severe adverse systemic reactions in patients who receive immunotherapy for perennial allergic rhinitis. The incidence of systemic reactions in those who had a high level of IgE (higher than 1000 U/ml) and asthma and/or atopic dermatitis was 66.67% (12/18) per patient. Conversely, the incidence of systemic reactions in those who had none of the risk factors was 1.64% per patient. Thus, the rate of systemic reactions is thought to be reduced by 75% if patients with high risk factors are strictly excluded from immunotherapy for allergic rhinitis.