[Study on immunotherapy safety: clinical practice in allergy outpatient care]

Immunotherapy with specific allergens is the only immune system-modifying treatment for allergic disease.

To identify the prevalence of adverse reactions during the subcutaneous immunotherapy initiation phase in real-life conditions and possible associated risk factors.

One-year retrospective, observational study. Epidemiological characteristics of 481 patients, type of immunotherapy used and adverse reactions were recorded.

16.8% of patients suffered atopic dermatitis, 8.9% food allergy, 4% drug allergy and 7.3 % had experienced idiopathic urticaria. Grass pollen was the main allergen. In polysensitized patients, the use of polymerized extracts that contained grasses in their composition was higher (89.2%) than that of native extracts (78.9%). A total of 1292 doses of specific immunotherapy were administered: 881 polymerized extracts and 411 depot extracts; 30 patients had an adverse reaction (6.2 %): 4.4% of those who received polymerized extract and 14.3 % of those who received a native one (OR = 3.657). In patients who received polymerized extracts, the adverse reaction was local in 82.4%, mild systemic in 11.8% and only in one it was serious systemic; 66.7 % of those who received native extract had local reactions, 25 % mild systemic and only one, serious systemic.

Subcutaneous immunotherapy under real life conditions is not free of risk, but the incidence of severe reactions is very low, especially with polymerized extracts, even when grouped or ultra-rapid testing is used.