Investigators from multiple institutions conducted a study to assess antibiotic usage, risk of allergic reaction, and cost savings in children previously classified as “penicillin allergic” who were “de-labeled” following penicillin allergy testing. The authors followed up a group of 100 children, labeled as penicillin allergic, who underwent 3-stage penicillin allergy testing in a previous study.¹ For that study, only children with symptoms considered low risk were enrolled; all 100 were de-labeled as penicillin allergic based on allergy testing results. For the current project, parents of the 100 children were contacted and asked about antibiotic prescriptions for their child subsequent to being de-labeled. Each child’s primary care provider was contacted to confirm the antibiotic prescriptions identified by the parent and any symptoms of allergic reactions.

Data on the following antibiotics were collected for cost analyses: amoxicillin, amoxicillin/clavulanate, azithromycin, cefadroxil, cefdinir, and penicillin. The cost of each prescription for study participants was estimated by using the median retail costs of each drug and assuming standard dosing regimen using the liquid form. Total dose was based on a hypothetical 8-year-old child (the median age of study participants) whose weight was at the 50th percentile for age. To assess cost savings, the authors calculated the actual costs of the antibiotics among the study cohort during follow-up and subtracted this total from the anticipated costs if none of the children had received a penicillin antibiotic. They also estimated cost avoidance, which was defined as the difference in cost if all of the study children who were prescribed amoxicillin received cefdinir instead.

Data were collected on 81 of the original 100 study children with a median follow-up time of 1 year since penicillin allergy testing. During the follow-up period, 36 study children received prescriptions for 46 antibiotics, including amoxicillin 24 prescriptions (52%), azithromycin 13 (28%), cefdinir 6 (13%), amoxicillin/clavulanate 2 (4%), and cefadroxil 1 (2%). Based on the distribution of antibiotic prescriptions in the study cohort, cost savings were estimated as $1,368. Cost avoidance (money saved among the 24 children prescribed amoxicillin instead of cefdinir) was calculated as $1,812. Among children receiving a penicillin antibiotic, 1 (4%) developed a rash approximately 24 hours after starting amoxicillin and was relabeled as penicillin allergic.

The authors conclude that many children with low-risk symptoms who were de-labeled as “penicillin allergic” received penicillin antibiotics without serious allergic reactions, leading to health care cost savings.