The reported prevalence of penicillin allergy in the US adult population ranges between 10-20%. However, when evaluated, fewer than 1% of the population has a true allergy. The objective of this study is to determine the impact on physician prescribing patterns, after patients presenting to the emergency department with a stated history of penicillin allergy undergo allergy risk stratification following a structured interview by a clinical pharmacist. This is a prospective, pilot study of all patients over the age of 18 with a stated allergy to penicillin presenting to the emergency department during the hours a clinical pharmacist is on-duty (N = 44). The study site is a suburban, academic, tertiary-care center with an annual volume of 80, 000 visits. Patients identified as penicillin allergic were interviewed by a clinical pharmacist using a nine-question, structured interview to determine allergy risk stratification (low, medium, high). The questionnaire results and risk stratification were entered into the electronic medical record for physician reference. Physicians then made an independent decision to use a beta-lactam versus a non-beta-lactam alternative if the patient required antibiotic treatment during their course of care. The overall sample demographic characteristics consisted of 68.2% females and 31.8% males, 15.9% African American, 15.9% Other/Multiracial, 68.2% White, age range 28-90 (M = 56.4, SD = 13.4). With regard to their allergy, 77.3% reported it occurred greater than 10 years ago, with 52.3% reporting rash only, and 31.8% having additional medication allergies. Risk stratification of the entire group yielded 56.8% low risk, 25.0% medium risk, and 18.2% high risk. A total of 52.3% (n = 23) of the interviewed patients required antibiotic treatment for infections (26.1% genitourinary, 26.1% sepsis, 21.7% respiratory, 13.0% skin, 13.0% gastrointestinal). Risk stratification of the treatment group yielded 60.9% low risk, 17.4% medium risk, and 21.7% high risk. Physicians prescribed a beta-lactam to 87.0% of the patients in the treatment group (n = 20) without any adverse outcomes (low-risk: n = 14, medium-risk: n = 2, high-risk: n = 4). Penicillin allergy labeling may incorrectly follow a patient creating downstream negative impacts including exposure to broad spectrum antibiotics, increased rates of antibiotic resistance, and prolonged hospital stays. The results of this study suggest using a pharmacy-driven, structured interview format to risk stratify patients, increases the likelihood that they will receive a beta-lactam during their treatment. Future studies with larger samples are needed in order to capture the potential outcomes and better understand the number of individuals who are truly allergic to penicillin and whether the structured interview is a more accurate screening tool than self-report.
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