Retrospective study of drug-induced anaphylaxis treated in the emergency department or hospital: patient characteristics, management, and 1-year follow-up.

BACKGROUND: Drugs are a common cause of anaphylaxis, which is potentially life threatening.

OBJECTIVE: We sought to describe US patients with an emergency department (ED) visit or hospitalization for drug-induced anaphylaxis (DIA), including postdischarge follow-up care.

METHODS: By using International Classification of Diseases, Ninth Revision codes in the MarketScan Database, we identified all patients with an ED visit and/or hospitalization for DIA between 2002 and 2008 (index date = initial ED visit and/or hospitalization). Inclusion required continuous full insurance coverage ≥1 year in the pre- and postindex period. We examined patient factors during the preindex period, characteristics of the index event, and outcomes during the postindex period.

RESULTS: The cohort included 716 patients with an ED visit and/or hospitalization for DIA (mean age, 48 years; 71% women). Most patients (71%) were managed in the ED, and only 8% of the patients with DIA treated in the ED received epinephrine. For those admitted, patients were hospitalized for a median of 3 days, and 41% spent time in the intensive care unit. Cardiorespiratory failure occurred in 5% of the patients in the ED and 23% of the patients who were hospitalized. The patients with a concomitant allergic condition were more likely to see an allergist/immunologist than those without a concomitant allergic condition, but 82% did not receive any subsequent care with an allergist/immunologist in the 1 year after the ED visit and/or hospitalization for DIA.

CONCLUSION: Drugs are a common, yet under-recognized, cause of anaphylaxis. Only a small number of patients with DIA received epinephrine in the ED or had subsequent care with an allergist/immunologist. These findings are novel and identify areas for improvement in the care of individuals with DIA.