Impact of β-Lactam Allergies on Antimicrobial Selection in an Outpatient Setting

The primary objective of this study was to determine whether patients prescribed nonpreferred antibiotics received appropriate alternative antibiotics.

This was a retrospective observational analysis of military veteran patients with a β-lactam allergy treated in an outpatient clinic or emergency department for an infection during a 5-year span. Antibiotic regimens were first stratified as preferred or nonpreferred based on infection-specific guidelines. The nonpreferred regimens were then evaluated for appropriateness based on allergy history and culture and sensitivity reports.

Of 445 fills of antibiotics evaluated, 269 met inclusion criteria, comprising 253 unique infections in 80 patients. Patients received nonpreferred antibiotics for their infection type in 57% of cases. Of the nonpreferred antibiotics, 56% were inappropriate based on guideline-recommended alternatives, allergy history, and culture and sensitivity data. Of the 88 allergies, 97% were historical/self-reported and 48% were cutaneous. In addition, 39% of patients safely received β-lactam antibiotics after documentation of their allergy.

Patients with documented β-lactam allergies are at high risk of receiving nonpreferred and inappropriate antibiotics, and many reactions likely do not reflect true allergies. These data emphasize the negative impact of the "β-lactam allergy" label and the importance of reassessing allergies.