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

ABSTRACT

OBJECTIVE: The primary objective of this study was to determine whether patients prescribed nonpreferred antibiotics received appropriate alternative antibiotics. METHODS: This was a retrospective observational analysis of military veteran patients with a ß-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. RESULTS: 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 ß-lactam antibiotics after documentation of their allergy. CONCLUSIONS: Patients with documented ß-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 "ß-lactam allergy" label and the importance of reassessing allergies.