Diagnostic Accuracy Of Different Commercial Walnut Extracts In A Paediatric Atopic Population

Walnut is a relevant allergenic food in paediatric population. An accurate diagnosis is essential. The aim of this study was to assess the diagnostic capacity of natural and three commercial walnut extracts to perform skin prick tests (SPT). Fifty-one atopic children were included in the study; 39 with a clinical history of walnut allergy and positive specific IgE values to walnut (≥ 0.35 KU/L) and 12 atopic controls tolerating walnut. SPT whit three commercial walnut extracts (ALK®, Leti®, Roxall®) as well as prick-prick test (PPT) with natural walnut were performed. Wheals ≥3 mm were considered positive. The sensitivity and specificity for SPTs with commercial extracts and natural walnut, as well as wheal sizes (WS), were analyzed. SPTs with ALK®, Roxall® and Leti® walnut extracts as well as natural walnut, showed high sensitivity (100; 100; 97.44; 100) but moderate to low specificity (75; 41.66; 41.66; 58,33) values with no differences between them. In walnut allergic patients, the median WS with Roxall's® walnut extract (9.5mm) was significantly larger than Leti's® (7.5mm; p <0.001) and ALK's® (7.5mm; p <0.001) but similar to those of the PPT (9.5mm; p = 0.566), while ALK's® and Leti's® WSs were significantly smaller compared to those of the PPT (p= 0,003; p<0,001). Commercial walnut extracts from ALK®, Roxall® and Leti® have a similar diagnostic accuracy.