Component-Resolved Diagnostics for Food Allergy - Twitter summary from EAACI-WAO Congress 2013

This summary was compiled from the tweets posted by allergists/immunologists who attended the EAACI-WAO Congress 2013. The tweets were labeled #eaaciwao2013. The text was edited and modified by me.

Adnan Custovic (UK) discussed Component Resolved Diagnostics for Food Allergy:

We use words like allergy, atopy, hypersensitivity very imprecisely.

Sensitization is detectable allergen-specific IgE. It should not be based on outdated lower limit of detection.

Should gender and age be taken into account when interpreting allergy tests? Are there age- and gender-specific cutoff points? Probably, but current practice doesn't reflect this.

Remission of sensitization between ages 4 and 8 is associated with low sIgE levels. A level of 3.5 kU/L appears to be a threshold for persistence of sensitization, but more studies are needed. It is important to note that in 10–25% of food allergy reactions, sIgE can be undetectable by blood test (http://buff.ly/1e7HAmY).

Food allergy

Probability of food reaction increases with increasing sIgE. Of course, blood tests or skin tests alone are not diagnostic of food allergy, but should be interpreted along with clinical symptoms. We're getting better, though: Allergen source -- extract -- components.

8 foods cause 90% of food allergies (click to enlarge the image). The likelihood of a negative oral food challenge is shown in relation to the respective values of skin prick test (SPT) and serum IgE (sIgE):



Peanut allergy

In an unselected birth cohort in the UK, 12% were peanut sensitized, 2% had a history of reactivity, but 19% were avoiding peanut!

Oral food challenge (OFC) for peanut was performed, and patients were assigned to allergic vs tolerant: 80% of sensitized patients were challenged, only 25% of those were allergic.

The overwhelming majority of peanut allergic children were sensitized to Ara h 1, 2 or 3. The sIgE to Ara h2 is the strongest predictor

At age 8 yrs in this population, sIgE to Ara h2 of 0.35 kU/L was the best cutoff value. There may be different numbers in other populations. Every population needs there own cutoff levels.

Component testing also has value for egg and soy allergy. However the testing methodology matters.

Component testing may have most value in the evaluation of high risk patients who have not yet experienced a reaction. Example: a sibling with a high sIgE.

Below is a marketing video from ImmunoCAP Peanut Component test. From the test manufacturer's YouTube channel: "The mother of a patient shared the story of her son who was diagnosed with multiple food allergies as an infant. After a peanut allergy diagnosis, the family's world was turned upside down. Recently, when starting Kindergarten, his doctor recommended the ImmunoCAP Peanut Component tests and, like 75% of all peanut sensitized individuals, the test results indicated he was not clinically allergic. He can now eat peanuts without fear."



Allergists are on Twitter - follow them

Allergists increased use of Twitter by 470% between 2011 and 2012. The service is very efficient in spreading the news from the annual scientific meetings, for example, 25 allergists reached 250,000 individuals from the 2012 #AAAAI meeting (see the references here).

This summary was compiled from some of the tweets posted by the following allergists:

Allergy Nurse ‏@AllergyNurseUK
Sakina Bajowala, M.D ‏@allergistmommy

This is a list of the allergists who used Twitter to post updates from the 2013 #AAAAI meeting. The list is open for edit, please feel free to add your own info.