Omar E Mohamed1, Sarah Beck2, Aarnoud Huissoon2, Cathryn Melchior2, Jane Heslegrave2, Richard Baretto2, Anjali Ekbote2, Mamidipudi Thirumala Krishna3. 1. Department of Allergy and Immunology, Heart of England NHS Foundation Trust, Birmingham, United Kingdom. Electronic address: omar.mohamed@heartofengland.nhs.uk. 2. Department of Allergy and Immunology, Heart of England NHS Foundation Trust, Birmingham, United Kingdom. 3. Department of Allergy and Immunology, Heart of England NHS Foundation Trust, Birmingham, United Kingdom; Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom.
Abstract
BACKGROUND: A spurious label of penicillin allergy (Pen-A) negatively impacts on antibiotic stewardship and health care costs. Recent studies have proposed a guideline-steered direct penicillin challenge without undertaking allergy tests when "true allergy" is unlikely. OBJECTIVE: To critically analyze Pen-A clinical presentation, perform risk stratification, and determine clinical predictors for "true allergy." METHOD: Data were extracted retrospectively from clinical and electronic patient records. RESULTS: A total of 231 patients (M = 82; F =149; mean age 51.22 [standard deviation ± 18.07] years) were analyzed. Based on clinical history, patients were categorized as likely type I hypersensitivity reaction (HSR) (n = 27), likely type IV HSR (n = 65), indeterminate (n = 111), and HSR unlikely (n = 28). Based on an index reaction and comorbidities, patients were classified into "low risk" (n = 143) and "high risk" (n = 78). Pen-A was excluded in 74% of patients assessed having likely type I HSR, 91% with likely type IV HSR, 93% of indeterminate, and 100% of HSR unlikely patients. The negative predictive value for successful delabeling in the "low risk" group was 94% (odds ratio [OR] = 2.9; P = .02). Predictors for "true Pen-A" were history of anaphylaxis (OR = 30.6; P < .001), hospitalization (OR = 7; P < .001), ≤5 years since the index reaction (OR = 3; P = .04). CONCLUSIONS: Systematic clinical characterization and risk stratification has an important role in Pen-A delabeling. These data provide proof of concept for a guideline-based selection of patients labeled with Pen-A for a direct penicillin challenge. Patients in the "low risk" group seem suitable for this intervention, although a rigorous prospective evaluation is needed in a multicenter study.
BACKGROUND: A spurious label of penicillinallergy (Pen-A) negatively impacts on antibiotic stewardship and health care costs. Recent studies have proposed a guideline-steered direct penicillin challenge without undertaking allergy tests when "true allergy" is unlikely. OBJECTIVE: To critically analyze Pen-A clinical presentation, perform risk stratification, and determine clinical predictors for "true allergy." METHOD: Data were extracted retrospectively from clinical and electronic patient records. RESULTS: A total of 231 patients (M = 82; F =149; mean age 51.22 [standard deviation ± 18.07] years) were analyzed. Based on clinical history, patients were categorized as likely type I hypersensitivity reaction (HSR) (n = 27), likely type IV HSR (n = 65), indeterminate (n = 111), and HSR unlikely (n = 28). Based on an index reaction and comorbidities, patients were classified into "low risk" (n = 143) and "high risk" (n = 78). Pen-A was excluded in 74% of patients assessed having likely type I HSR, 91% with likely type IV HSR, 93% of indeterminate, and 100% of HSR unlikely patients. The negative predictive value for successful delabeling in the "low risk" group was 94% (odds ratio [OR] = 2.9; P = .02). Predictors for "true Pen-A" were history of anaphylaxis (OR = 30.6; P < .001), hospitalization (OR = 7; P < .001), ≤5 years since the index reaction (OR = 3; P = .04). CONCLUSIONS: Systematic clinical characterization and risk stratification has an important role in Pen-A delabeling. These data provide proof of concept for a guideline-based selection of patients labeled with Pen-A for a direct penicillin challenge. Patients in the "low risk" group seem suitable for this intervention, although a rigorous prospective evaluation is needed in a multicenter study.