One day versus five day drug provocation tests in mild delayed cutaneous beta lactam reactions in children: Negative predictive value and real‐life reuse outcomes

BACKGROUND: Although drug provocation test (DPT) is the gold standard for diagnosing beta-lactam hypersensitivity (BLHS), its optimal duration in mild non-immediate cutaneous reactions remains uncertain. We compared the outcomes and negative predictive values (NPVs) of one-day versus five-day DPT protocols in children with suspected mild non-immediate cutaneous BLHS. METHODS: We retrospectively reviewed patients (<18 years) evaluated between 2016 and 2023 for mild nonimmediate cutaneous BLHS. Our unit used a five-day extended DPT protocol in earlier years and subsequently adopted a one-day protocol as routine practice. Therefore, protocol assignment was period-based. Demographics, index reaction features, culprit drugs, DPT results, and real-life re-exposure outcomes were recorded. Repeat DPT, when performed, was used to adjudicate true allergy and estimate final NPV. RESULTS: A total of 173 children (median age 7 years; IQR 4-10.5; 50.9% female) were included. DPT was performed a median of 11 months after the index reaction. One-day and five-day protocols were applied in 92 (53.2%) and 81 (46.8%) patients, respectively. Objective reactions during DPT occurred in 10/173 (5.8%) (positive DPT). Among 163 patients with negative DPT, 95 (58.3%) reported re-exposure; 10/95 (10.5%) experienced recurrent symptoms (6 one-day vs. 4 five-day; p = .768). Five underwent re-provocation, with one confirmed positive. Final NPVs were 93.1% for the one-day protocol and 98% for the five-day protocol (p = .333). CONCLUSION: In this period-based retrospective cohort of selected low-risk children with mild non-immediate cutaneous beta-lactam allergy, one-day and five-day DPT protocols yielded comparable NPVs. A single-day protocol appears feasible for appropriately selected patients, although prospective studies are warranted.