Penicillin allergy evaluations improve antibiotic utilization, but penicillin skin testing (PST) requires more resources than challenge alone. Because amoxicillin challenge without preceding PST may be safe in low-risk patients, we assessed a risk stratification tool for outpatient penicillin allergy evaluations.
A prospective observational study of adult patients with penicillin allergy histories was conducted. Patient demographics and penicillin allergy history were reviewed. The risk stratification tool uses the allergy history: low-risk patients (i.e. without IgE features) undergo two-step amoxicillin challenge only; intermediate-risk patients (i.e. IgE features, or anaphylaxis > 5 years ago) undergo PST and, if negative, one-step amoxicillin challenge; and high-risk patients (i.e. recent anaphylaxis) either avoid penicillin or receive desensitization. Outcomes of allergy evaluation were compared between groups.
Of 159 patients (mean age 48 years, 74% female), 33 were low-risk, 126 were intermediate-risk, and none were high-risk. The intermediate-risk group most often reported hives (54%), rash (40%), dyspnea (11%), and/or swelling (10%). The low-risk group most often reported rash (55%) or unknown (36%). All low-risk patients tolerated challenge without reaction. All intermediate-risk patients were PST negative and tolerated challenge; one patient (0.8%) developed a delayed rash. Most patients (155/158, 98%) were appropriately de-labelled of penicillin allergy in the electronic health record, but two patients had the allergy reentered by non-allergists.
A novel risk stratification tool for penicillin allergy evaluation permits low-risk patients to be de-labelled safely without PST. Broader implementation of this tool may enable more penicillin allergy evaluations to be performed, but documentation challenges persist.