Is your Eczema Child (Wrongly) Avoiding a Tested-Positive Food in SPT?

Skin Prick Test (SPT)

If your child has eczema and has been avoiding a food that he/she has been tested positive in the Skin Prick Test (SPT), it may be time to review if there is indeed a true food allergy. Research indicates, as I understand from various online articles, that the skin prick test is a test of sensitization, and not clinical relevance. Below are some points on the accuracy of skin prick test:

1.      Skin Prick Test is more accurate for non-food allergen, such as dust mite and pollen, than for food allergen.

2.      Skin Prick Test is More Accurate in predicting when there is NO food allergy and Less Accurate in predicting a Positive food allergy. The implication of this is that children who have been avoiding food (for example more than 50% of those tested positive for milk and eggs, and more than 70% of those tested positive for peanuts) actually didn’t have an allergic reaction to these foods. (There is only a 0.5-10% chance that a child who is allergic to a food will test negative for it.)

3.      Follow-up tests are required for skin prick test for children at different age, sometimes about 1-2 years later. The results can be different as children may ‘outgrow’ some allergy or develop new ones? (hopefully not…)

4.      An oral food challenge is the most accurate (less than 5% incorrect).

5.      For children with eczema, there is an 80% possibility that food that the child is avoiding turn out not to be one he/she is allergic to. Refer to this article for detailed research.

Despite above, Skin Prick Test still remains the most recommended first test for allergy, as it is by comparison simpler, lower cost, faster results, more tolerated (children won’t feel much pain, you can read this post on my baby Marcie’s experience) and more accurate than blood test. If anyone has an experience to share on skin prick test for your child, do comment below this post.

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5 thoughts on “Is your Eczema Child (Wrongly) Avoiding a Tested-Positive Food in SPT?

  1. Just a question , have you heard about the RAST blood test, have you ever tried on your son ? Was wondering ? as i am thinking of taking my son to do the test

  2. Hi Anicia, I’ve heard about the blood test and I’ve never tried it on my baby. What I know about blood test is that it is generally less accurate than skin prick test, but able to tell better how allergic (the degree of sensitivity) the child is to the substance. I visited your blog and all the best to managing your child’s eczema. You’re welcome to sign up in the ‘contact me’ form and join our support group. Take care!

  3. Hi,

    Reading this post makes me a bit relief yet confused. I took my son for SPT when he was 7 month-old. It turned out he allergic to so many foods. I didn’t see a dietitian, I was just avoiding all the food. Reading this I feel there’s still hope to introduce some foods, but I am still worried for the reaction. Is there any suggestions beside seeing the dietitian? My son is 1-year old npw. We’re going to have another SPT next May. Please suggest, what do I need to ask after I get the result? Thank you so much!

  4. Hi Temee,

    Is the other SPT scheduled coming May or 2014 May? If it’s the coming May, do wait for the test result before introducing the foods tested allergic the previous time. You can ask the doctor which are the ones he/she recommend you can introduce and what records he/she like you to keep in order for his evaluation on whether the food is triggering the eczema flare.

    Certain foods will cause more serious reaction than others, peanut is known to cause anaphylactic shock in children, so it’s best to ask the doctor which ones are considered safe for you to try. Or you can ask for alternatives to skin prick test, to see if there is a measure of the severity of allergic reaction – then from there it may be possible to try those not as severely allergic to (this however, I did not venture for my child cos her SPT were negative for all in first test).

    Take care!
    Mei

  5. Pingback: Friday Dr Q&A with Dr Liew – Allergy Tests | Eczema Blues

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