The fraction of exhaled nitric oxide improves prediction of clinical allergic reaction to peanut challenge in children

Summary Background Retrospective studies of childhood peanut allergy demonstrate serum‐specific IgE ( I g E ) levels against the peanut allergen A ra h2 may help predict a clinical reaction at food challenge. Fraction of exhaled nitric oxide ( F e NO ) is a non‐invasive tool correlating to allergic airways inflammation and has been independently associated with increased food‐specific I g E . Objective To assess the validity of serum‐specific A ra h2 I g E measured prospectively to diagnose peanut allergy and explore the utility of Fe NO as a non‐invasive screening tool for childhood food challenge. Methods We recruited 53 participants from a cohort of consecutive children scheduled for an open‐labelled peanut food challenge ( OFC ) by their paediatric allergist. Participants underwent skin prick test ( SPT ) measurement for sensitization to whole peanut extract, and serum was collected for A ra h2‐specific I g E . Fe NO was also measured in all cooperative children before the challenge. OFC and assessment of reaction were undertaken by clinicians blinded to test results. Results A ra h2‐specific I g E and F e NO each showed improved diagnostic accuracy when compared to SPT . Receiver operator characteristic curve analysis gave an area under the curve ( AUC ) for A ra h2 s I g E of 0.84 (95% CI, 0.72–0.96). The AUC for F e NO , 0.83 (95% CI, 0.71–0.95), was equivalent to that of A ra h2. Combined AUC for SPT , s I g E to A ra h2 and F e NO was 0.96 (95% CI 0.90–1.00). There was no correlation between F e NO and serum nitrite levels (rs = −0.13, P  = 0.6, n  = 18). Conclusion and clinical relevance Prospectively measured A ra h2‐specific I g E improves diagnostic accuracy and reduces unsuccessful challenge to peanut. F e NO levels may provide improved diagnostic accuracy in a paediatric population undergoing OFC . The proposed FeNO‐based diagnostic algorithm requires further validation studies.