Objective: Beta-lactam antibiotic allergies are reported in 5%-10% of children; however, up to 90% do not have any reaction at oral challenge test (OCT). This study aimed to determine the frequency and identify predictors of positive in-hospital graded beta-lactam OCTs in children with a beta-lactam antibiotic allergy label (AAL).

Design: This is a retrospective study conducted over 7 years, including children aged 0-19 years who underwent a beta-lactam OCT. The OCT comprised an in-hospital graded challenge followed by a 5-day outpatient antibiotic course. Univariate and multivariate logistic regression analyses were performed to identify predictors of a positive in-hospital graded OCT.

Results: Overall, 1259 beta-lactam OCTs were included: median age at time of OCT was 6.3 years (range 8.8 months to 19.2 years). Of these, 18 (1.4%) in-hospital graded OCTs were positive and 10 (0.8%) were equivocal, with only 4 children (0.3%) having an immediate, severe reaction to their in-hospital graded OCT. Factors associated with a positive in-hospital graded OCT on univariate analysis were: history of other drug allergy (OR 2.7, 95% CI 1.0 to 7.2; p 0.05), an index reaction which was severe (OR 2.9, 95% CI 1.1 to 7.6; p 0.035), immediate and severe (OR 5.85, 95% CI 1.7 to 20.0; p 0.005) or that required epinephrine (OR 9.65, 95% CI 1.7 to 53.6; p 0.01).

Conclusion: Of the children referred with a beta-lactam AAL, only 1.4% had a positive in-hospital graded OCT. Risk factors for a positive in-hospital graded OCT were history of other drug allergy, an index reaction which was severe, immediate and severe or required epinephrine.