Objectives: To contrast the initial suspected etiology of anaphylaxis with the postworkup diagnosis in patients attended at the emergency department (ED) of a tertiary-level hospital in Spain and to investigate the incidence, causes, and management of anaphylaxis.

Methods: We performed an observational study of patients aged more than 15 years who came to the ED with anaphylaxis between 2009 and 2010. All clinical records from the ED were reviewed. We recorded data on clinical management, the etiology proposed by the attending emergency physician, and the cause reported by the patient. The findings were compared with the diagnosis reached after the allergy workup.

Results: The incidence of anaphylaxis was 0.08%. The most common manifestation was skin-mucosal symptoms (98.3%). Anaphylaxis was diagnosed in the ED in only 44% of the cases, regardless of severity. Only 39.7% received epinephrine, which was administered more frequently when the ED physician diagnosed anaphylaxis, regardless of severity. A total of 60 patients were subsequently seen at the allergy department. The final etiology differed from the initial suspicion in the ED in 45% of cases. The frequency of anaphylaxis of uncertain origin decreased from 33.3% to 13.3%. After the allergy workup, drugs (41.7%) were considered the main cause of anaphylaxis, followed by food (25%).

Conclusions: The incidence of anaphylaxis (0.08%) was double that estimated in the ED. Anaphylaxis is underdiagnosed. A correct diagnosis conditions the administration of epinephrine, regardless of the severity of symptoms. The real etiology of anaphylaxis should only be proposed after an allergy workup, which is recommended in all cases, as the real cause can differ considerably from the initial impression in the ED.

Key words: Anaphylaxis. Drug allergy. Emergency department. Epidemiology. Food allergy. Etiology. Allergy study. Comparison.