The NutCracker Study
: a study of incidental sensitisation to peanut in egg allergic children, and the utility of component-resolved diagnostic testing to Ara h 2 in predicting clinical outcome

  • Deb Marriage

Student thesis: Doctoral ThesisDoctor of Health (DHealth)


Peanut allergy affects 1-2% of UK schoolchildren. Children with egg allergy are at increased risk. The diagnosis of peanut allergy in this group of children is challenging, with current diagnostic techniques being inadequate. Clarification of peanut allergy status in egg-allergic, peanut-sensitised children is complicated and frequently includes the need for an oral provocation challenge. This places considerable pressure on day-case services, poses a potential risk to the child and carries health economic implications. Recent research has proposed the measurement of specific IgE concentrations to the peanut component Ara h 2 to be a better test for the differentiation of allergy and tolerance than existing methods.The present study attempts to improve the diagnostic process for this group of children. The primary aim was to investigate the diagnostic value of measuring Ara h 2-specific IgE concentrations in predicting a clinical reaction to peanut. 105 eligible children were prospectively recruited via the tertiary allergy clinic at Bristol Royal Hospital for Children. Children were subjected to a peanut skin prick test and specific IgE testing to whole peanut and Ara h 2 followed by an oral provocation challenge. Children were allocated to either the peanut allergic or tolerant group. Outcomes were related to all three tests.The peanut skin prick test and whole-peanut specific IgE were poor discriminators between allergy and tolerance. Ara h 2 was the best predictor of peanut allergy, but had greater clinical utility as part of a two-step approach. Receiver-operator curve construction identified optimal cut-off values of 6mm for peanut skin prick testing, 0.39kUA/L for Ara h 2-specific IgE concentrations and 1.08kUA/L for whole peanut specific IgE. These were included in a diagnostic two-step model. When used in isolation, specific IgE concentrations to Ara h 2 were unable to replace the need for an oral provocation challenge for the majority of egg-allergic, peanut-sensitised children.
Date of Award26 Apr 2017
Original languageEnglish
Awarding Institution
  • University of Bath
SupervisorJames Turner (Supervisor) & John Henderson (Supervisor)

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