Unreliable allergy tests spark call for standardisation

Australian scientists are calling for the standardisation of allergy tests, after laboratory trials published in the journal Allergy showed that commercially available tests are not uniformly reliable.

As noted by study leader Dr Thimo Ruethers, from James Cook University’s (JCU) Australian Institute of Tropical Health and Medicine and Tropical Futures Institute, food allergies pose major public health concerns, lower the quality of life and can be fatal. This is particularly the case with shellfish allergy, which affects up to 3% of the general population, is usually lifelong and commonly triggers anaphylaxis — a condition that leads to respiratory collapse.

“Skin prick testing (SPT) is often the preferred first-line diagnostic approach,” said Professor Dianne Campbell from The Children’s Hospital at Westmead. “This involves a health worker placing a drop of allergen extract on the surface of the arm then pricking through it into the arm. If you are allergic to the allergen you will have a small, itchy swelling and a reddening of the skin after 10–15 minutes.”

But widely utilised allergen extracts in commercial SPT kits are generally not standardised, with JCU group leader Professor Andreas Lopata noting that researchers demonstrated “considerable variability in effectiveness” for 27 commercial SPT extracts for fish allergy in a 2019 study. This limits the diagnostic value of results.

“In the current study, using biochemical and immunological methods and mass spectrometry, we tested 11 commercial crustacean and five mollusc SPT extracts and found even greater, critical variability in their reliability,” Lopata said.

Dr Thimo Ruethers presents the research findings published in Allergy.

The scientists concluded that some of the SPT extracts lacked the sufficient amount and diversity of important shellfish allergens, meaning test results could be falsely negative and putting lives at risk.

“Standardisation of allergen extracts is urgently needed to improve the accuracy and reliability of SPTs,” Ruethers said.

“Also, improvements in blood tests, along with the development of region-specific allergen extracts with known quantities of clinically well-characterised allergen components, are critical to achieve considerable improvements in allergy testing.”

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