Specificity of allergen skin testing in predicting positive open food challenges to milk, egg and peanut in children

Clin Exp Allergy. 2000 Nov;30(11):1540-6. doi: 10.1046/j.1365-2222.2000.00928.x.


Background: The specificity of allergen skin prick testing to diagnose clinically relevant food allergy is controversial.

Objectives: To determine the specificity of the allergen weal diameter to correctly identify children who react on formal open food challenges.

Methods: Over a 9-year period children referred to a tertiary allergy clinic for the evaluation of suspected food allergy were prospectively studied. Allergen skin prick testing to cow milk, egg white and peanut extracts (Dome-Hollister-Stier, Spokane, WA, USA) was undertaken using a lancet technique. All children underwent open food challenges to the relevant food(s) in a hospital clinic. Challenges were classified as positive, if objective signs were seen; negative, if the child could tolerate normal quantities of the food, daily, for one week; or inconclusive if none of the former criteria were met.

Results: Five hundred and fifty-five challenges were undertaken in 467 children: 339 challenges to cow milk, 121 to egg, and 95 to peanut. Fifty-five percentage of challenges were positive, 37% negative, and 8% inconclusive. For each food it was possible to identify a skin weal diameter at, and above, which negative reactions did not occur: cow milk, 8 mm; egg, 7 mm; peanut, 8 mm. In contrast, positive reactions could occur with a skin wheal diameter of 0 mm.

Conclusions: In this high risk referral population it was possible to define skin weal diameters to egg, milk and peanut above which open oral food challenges were positive (100% specificity). By utilizing these measurements the need for formal food challenges can be reduced.

MeSH terms

  • Animals
  • Arachis / adverse effects*
  • Child, Preschool
  • Eggs / adverse effects*
  • Female
  • Food Hypersensitivity / diagnosis*
  • Humans
  • Male
  • Milk Hypersensitivity / diagnosis*
  • Prospective Studies
  • Sensitivity and Specificity*
  • Skin Tests*