Scientific Study

Background. Although allergy to tree nuts is often considered a single entity, there is heterogeneity in patient reactivity and immune response to different tree nuts. Objective. We sought to characterize tree nut oral food challenges (OFC) in a pediatric population performed at a single center over a 12-year period and determine differences in OFC outcome to different tree nuts. Methods. A retrospective chart review was conducted in patients (0- 20 years) who completed an unblinded OFC to any tree nut from 2007-2019 at Lurie Chlildren’s Hospital of Chicago. Differences among almond, cashew, hazelnut, and walnut challenges were compared and probability curves were used to estimate positive predictive values (PPV) of specific IgE (sIgE) at OFC. Results. 531 tree nut OFCs were included. The mean age at OFC was 7.77 years (SD 4.33). Overall, 74.0% of children passed clinically indicated OFCs. Of the four most commonly challenged tree nuts, almost all patients passed OFC to almond (97.3%) and hazelnut (87.9%). Pass rates were lower for cashew (65.3%) and walnut (57.0%), p<0.0001. The odds of failure were 0.83 times lower for patients who were avoiding without a previous reaction compared to those who had previously reacted (p=0.0025). Conclusions. The majority of patients pass low risk almond and hazelnut OFCs. PPV at the 50th percentile for walnut (2.84 kU/L) and cashew (3.35 kU/L) were lower than previous studies have suggested. https://doi.org/10.1016/j.jaip.2021.05.035