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Skin-prick testing may replace oral food challenges in certain screening programs

Oral food challenges may be replaced by skin-prick testing in population-based studies and may also be helpful in community screening programs when allergy prevalence is relatively low, according to late-breaking results of an Australian study presented during the 2011 Annual Meeting of the American Academy of Allergy, Asthma & Immunology conducted this week in San Francisco.

The population-based HealthNuts study of pediatric food allergy recruited infants aged 12 months from council-led immunization sessions in Melbourne. All participants were offered skin-prick testing to raw egg white, peanut and sesame. All infants with skin-prick testing of at least 1 mm were invited to the Royal Children’s Hospital for an oral food challenge. Infants with raw egg allergy were subsequently offered a baked egg challenge. All participants with a negative skin-prick test and no history of food reactions were considered as nonfood allergic. Diagnostic characteristics were determined using receiver operating characteristic curves and logistic regression.

Data showed that of 3,752 parents approached, 2,557 agreed to skin-prick testing; the 95% positive predictive value for raw egg white was a wheal size of 5 mm (95% CI, 4-6; allergy prevalence, 9%). The corresponding 95% positive predictive value for baked egg allergy was 10 mm (95% CI, 9-11); peanut allergy was 9 mm (95% CI, 8-10; prevalence, 2.9%); and sesame allergy was 8 mm (95% CI, 7-9; prevalence, 0.7%).

Thresholds for skin-prick test wheal size with 95% positive predictive value for food allergy have been developed in clinic settings to aid diagnosis of food allergy and minimize the need for resource-intensive oral food challenges. However, their value as a community screening tool in diagnosing food allergy and as a surrogate marker in population-based studies has not been formally investigated, according to the researchers from The University of Melbourne and Royal Children’s Hospital, Melbourne.

For more information:

• Gurrin LC. Abstract #L1 Presented at: 2011 Annual Meeting of the American Academy of Allergy, Asthma & Immunology. March 18-22. San Francisco.

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