PEAnut Anaphylaxis Predictors

Children aged 2-17 years with suspected peanut allergy will be invited to participate in the study.

They will have a questionnaire, a skin prick test to peanut, 2 breathing tests (spirometry and fraction of exhaled nitric oxide (FeNO)), and a blood test (specific peanut antibodies, allergic immune responses - including the novel blood biomarker - and genetic testing to identify novel potential molecular and genetic markers of food allergy in the future. The genetic testing component will be optional). The breathing test is not required for those under 6 years.

The final step is an open label peanut food challenge with incremental doses of peanut, (routine practise) as per the Australasian Society of Clinical Immunology and Allergy (ASCIA) food challenge protocol.The endpoints in the food challenge will be signs of allergy or anaphylaxis as per PRACTicing ALLergology (PRACTALL) consensus report for oral food challenges OR completion of the ASCIA food challenge protocol.

Outcome: The primary outcome of the project is to confirm that a novel blood biomarker has a higher diagnostic accuracy as compared to current best testing in predicting anaphylaxis at open label peanut challenge.

Secondary outcome: Will be to determine the value of the biomarker, FeNO and Ara h2 specific Immunoglobulin E (sIgE) (individually and in combination) at predicting anaphylaxis or clinical allergy at open label peanut challenge.

Inclusion criteria

• Children aged 2 - 17 years with an allergy to peanut and require peanut challenge to confirm peanut allergy.

Exclusion criteria

• Children with Peanut Skin Prick Test (SPT) wheal size greater than 10mm as these children are likely to have clinical peanut allergy (no clinical indication for food challenge).