Methods: Chart review of 297 patients with queried PA was conducted (June2013 - September2014). Medical history, skin prick testing (SPT), specific IgE and CRD to peanut (ara h1-3, ara h8 and ara h9) were used to classify patients as Probable (anaphylaxis + SPT>5mm), Likely (anaphylaxis + SPT>3mm, or no reaction + SPT>5mm), Unlikely (anaphylaxis + SPT<3mm, or unexposed + SPT<3mm) or no PA (history of tolerance, or unexposed + SPT<3mm). Threshold of peanut IgE where CRD is clinically relevant and the number with a change in PA were determined.
Results: Clinically relevant peanut CRD (defined as ara h1-3 of ≥0.35kU/L) if IgE Peanut ≤0.1kU/L is 2.6% (n=39), ≤0.2kU/L is 1.9% (n=52), and ≤0.35kU/L is 5.9% (n=68). When IgE peanut is >30kU/L (n=110), clinically relevant peanut CRD is always detected. Of 158 patients labeled Probable or Likely PA , 9.5% would be advised to have an oral food challenge based on CRD (ara h1-3 ≤0.35kU/L). Of the 95 patients labeled Unlikely or No PA, 52.6% would be reclassified as PA (ara h1-3 ≥0.35kU/L). If CRD is the only marker of PA in at risk patients, 49% of the study population would be considered PA.
Conclusions: CRD in suspected PA patients detects 10% of patients for food challenge. CRD overuse will inappropriately label half of patients at risk. Peanut CRD should be limited to peanut IgE ≤30kU/L; beyond which, management will not be altered.