Identifying Low-Risk Beta-Lactam Allergy Patients in a UK Tertiary Centre

BACKGROUND: There are marked geographical as well as temporal differences in patient sensitization profiles to beta-lactams (BL). OBJECTIVE: To determine the utility of skin test reagents and identify a cohort of patients where skin testing can be safely omitted in a cohort of patients referred to a UK tertiary referral center. METHODS: A retrospective study of the clinical characteristics of 1092 patients referred for BL allergy testing was analyzed using multivariate regression analysis. The effectiveness of skin test reagents was also evaluated. RESULTS: Multivariate logistic regression identified that a history of anaphylaxis (odds ratio [OR] 10.98, P = .001) and the patients' recall of the index drug (apart from ampicillin and meropenem, OR 3.51-12.43, P < .05) were independent predictors of type I BL allergic status and a time of less than 1 year elapsed since index reaction significantly increasing the odds of a patient with a history of anaphylaxis, having a type I BL allergy (OR 38.66, P = .003). An absence of anaphylactic severity, unknown name of the index drug and a reaction occurring more than 1 year before testing, has a negative predictive value (NPV) of 98.4%, which was similar to the NPV of skin testing of 98.9% for type I BL allergy. The NPV of skin testing with benzylpenicillin + amoxicillin +/- index BL was similar with (98.9%) or without (98.1%) the use of benzylpenicillin polylysine and minor determinant for type I BL allergy. CONCLUSION: We identified a "low risk" cohort of patients where the history is of similar reliability to skin testing in predicting nonallergic status for BL allergy. (C) 2019 American Academy of Allergy, Asthma & Immunology.