Which site is better? Comparing back vs arm SPTs in paediatric food challenges.

Abstract

Skin prick testing (SPT) is a commonly used test in IgEmediated food allergy and guides the decision to proceed with oral food challenges (OFCs) in paediatric practice. SPTs are typically performed on the back, leveraging the larger surface area and the practical advantage that young children are less likely to disrupt the test. However, evidence suggests that back-based SPTs may yield larger wheal sizes than those on the forearm, potentially overestimating clinical reactivity and leading to unnecessary avoidance or missed opportunities for OFC. No study has directly compared SPT wheal sizes at both sites (arm and back) in children undergoing OFC. This study aims to address this gap, evaluating whether arm based SPTs offer improved concordance with OFC outcomes than back based SPTs. The findings could have important implications for paediatric allergy diagnostics and patient care.