Almost one-quarter of ED visits or hospitalizations for anaphylaxis involved severe anaphylaxis, while preventive care the year before the event lowered that risk, according to recent study results.

Researchers used an expanded ICD-9-CM diagnosis algorithm to identify 11,927 patients (median age, 45 years; 58% female) from two databases who had an ED visit or hospitalization for anaphylaxis between 2002 and 2008. The patients had continuous medical and prescription coverage for at least 1 year before and after the event. Reaction requiring hospital admission was used to define severe anaphylaxis.

Twenty-two percent of patients had severe anaphylaxis, which was associated with older age and higher comorbidity burden, according to unadjusted analysis.

“These patients were also less likely to have filled an epinephrine autoinjector (EAI) prescription or visited an allergist/immunologist, but more likely to have had an ED visit/hospitalization (any cause),” the researchers wrote.