Unpacking Oral Challenge Protocols: A Descriptive Epidemiologic Study of Reactions, Predictors, and Practices for...

Background: Oral challenges with amoxicillin or other penicillins are safe and effective for delabeling low-risk penicillin allergy histories. While approximately 90% of reported penicillin allergies can be safely delabeled, detailed data on reaction frequency, types, and timing during and after delabeling interventions remain limited. Such data are crucial to optimizing protocols and integrating oral challenges into routine practice. This study aims to characterize the interventions commonly used for oral challenge, classify reported reactions, and identify reported predictors of hypersensitivity reactions in randomized controlled trials and quasi-experimental studies involving an oral challenge for patients with low-risk penicillin allergies. Methods: This study leverages data from a systematic review and meta-analysis assessing the effectiveness of oral challenge interventions in patients with low-risk penicillin allergies. This descriptive analysis summarizes the adverse reactions experienced among patients in published studies who received oral challenge. Participant demographics, intervention protocols, frequency, type, and timing of post-challenge adverse reactions are reported. Reactions are categorized as immediate, delayed, or other, with frequencies summarized using descriptive statistics. A random effects meta-analysis quantifies a pooled adverse reaction rate. Predictors of hypersensitivity reactions were synthesized narratively. Results: Across 26 studies (2 randomized trials, 24 quasi-experimental studies) evaluating an oral challenge for patients with a low-risk penicillin allergy, the average participant age was 56 years, with a predominance of females (61%) and limited ethnic diversity with 88% reported or identifying as White. Amoxicillin was the most frequenty used oral challenge agent, typically administered as a single 250 mg oral dose. The incidence of reaction or non-delabeling was 4% (95% Confidence Interval 3%, 6%), I ² = 43%, P = .0001. Cutaneous manifestations, such as rashes, were the most frequent reactions. Delayed reactions, primarily mild maculopapular rashes, were uncommon and managed with antihistamines or topical steroids. Risk factors for oral challenge reactions included higher baseline allergy burden and shorter intervals to oral challenge since the index reaction. Conclusion: Oral challenge strategies to delabel low-risk penicillin allergies can involve single doses of amoxicillin or other penicillins with monitoring protocols that can be managed in ambulatory settings. However, although these delabeling strategies are becoming more prevalent, continued study of standardized protocols and follow-up are essential for effective and replicable delabeling strategies. Future research should prioritize diverse populations and equity-driven frameworks to improve generalizability to all individuals and to resource limited settings.