Costs of beta-lactam allergies: selection and costs of antibiotics for patients with a reported beta-lactam allergy.

OBJECTIVE

To evaluate antibiotic selection and the cost effect of reported beta-lactam allergies.

DESIGN

Retrospective medical records review comparing antimicrobial selection and costs in patients with a reported beta-lactam allergy with a group in which no such allergy had been documented.

SETTING

University-based family medicine clinic.

PATIENTS

Patients who were prescribed at least 1 antibiotic for an upper respiratory tract infection, otitis media, sinusitis, and/or a urinary tract infection were eligible. One thousand two hundred one patients were identified via ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification) codes. Four hundred sixty-five patients were initially identified and an additional 195 family members were eligible for inclusion.

MAIN OUTCOME MEASURES

Comparison of antimicrobial selection and costs (by average wholesale price) between patients with and without a reported beta-lactam allergy.

RESULTS

Of the 660 patients eligible for inclusion, 99 (15%) had a documented beta-lactam allergy. Of the patients with a documented allergy, only 33% had a description of their purported reaction. The mean antibiotic cost for patients with a beta-lactam allergy was significantly higher compared with those without a beta-lactam allergy ($26.81 vs $16.28, respectively; P =.004). Patients with a beta-lactam allergy were more likely to have received a cephalosporin, macrolide, or a miscellaneous agent (eg, quinolone, tetracycline, or nitrofurantoin) (P =.001).

CONCLUSIONS

Patients with a beta-lactam allergy had higher antibiotic costs and were more likely to receive a broader-spectrum antibiotic. Most patients with a reported allergy did not have a description of their reaction. Skin testing may be of use in detecting true beta-lactam allergies; however, further study is needed to determine its cost-effectiveness.