Identification of patients eligible for penicillin skin test protocol

RATIONALE: Removing penicillin allergy from patient charts via negative skin testing has been shown to result in use of narrower spectrum antibiotics, more effective antibiotics, and more cost-effective therapy. Penicillin skin testing is a valuable test in patients with history of IgE-mediated reactions. We sought to identify how many patients in our institution had prior IgE-mediated reaction to penicillin, thus would benefit from implementation of a penicillin skin test protocol in our institution.

METHODS: A retrospective cohort study of patients >18 years admitted during January-February 2017 with documented penicillin allergy was performed. Type of reaction was documented in the electronic medical record (EMR) as anaphylaxis, rash, itching, hives, swelling, shortness of breath, or a "free-texted" comment. We grouped the reactions as undocumented, possibly IgE-mediated (any combination of anaphylaxis/rash/itching/hives/swelling/shortness of breath), and non-IgE mediated (thrombocytopenia, anxiety, stomach upset, acute interstitial nephritis, etc).

RESULTS: Of 183 patients who met the inclusion criteria, 32% (n=58) reactions were undocumented, 61% (n=112) possibly IgE-mediated, and 7% (n=13) non-IgE mediated. By combining the undocumented and possibly IgE-mediated reactions, we identified 93% (n=170) of patients with penicillin allergy over a two month period who would likely benefit from penicillin skin testing.

CONCLUSIONS: These patients require a more detailed history prior to skin testing because EMR does not distinguish between Type 1-4 reactions. Nonetheless, we identified a significant number of penicillin-allergic patients with possibly IgE-mediated reaction or undocumented reaction who would benefit from the implementation of an institution-wide penicillin skin test protocol.