Analysis of the Safety of Drug Allergy Workups in a Spanish University Hospital: Drug Characteristics, Type of Reaction, and Patients' Age at the Initial Assessment.

Introduction: The drug provocation test (DPT) is the gold standard for the drug allergy workup; however, it is not free from severe adverse reactions. Our aim was to obtain robust data that predict a reaction during or after the DPT at the first contact with the patient in the allergy outpatient clinic.

Methods: The population of this cross-sectional study comprised all patients undergoing a drug allergy workup (clinical assessment, specific IgE, or skin tests, or DPT) at University Hospital Fundacion Alcorcon in 2016. DPTs were performed until therapeutic doses were reached, and late reactions were checked. The clinical disorders assessed in our study were classified mainly as absence of allergic reactions, morbilliform rash, urticaria, anaphylaxis, and other cutaneous disorders.

Results: Physicians from the Allergy Unit programmed drug allergy workups in 977 patients (median age, 52 years; women, 64.54%). DPTs were not performed for 165 drugs involved in the reactions. Patients who did not undergo DPT were older than patients who did (positive or negative) (p = 0.0001). Positive DPT results were detected in 6.00% of DPTs performed, and most were for amoxicillin and metamizole (15-25% each). Multinomial logistic regression showed that positive reactions were more probable after DPT if the same clinical disorder was diagnosed at the first visit, including the episodes not considered allergic episodes (OR = 0.2, <0.01), except for anaphylaxis, which favored not performing DPTs (OR = 11, p < 0.001).

Conclusion: We conclude that clinical practice in the diagnosis of drug allergy in our Allergy Department is safe, without over-diagnosis.