The predictive value of the skin prick test weal size for the outcome of oral food challenges.
BACKGROUND
The skin prick test (SPT) is regarded as an important diagnostic measure in the diagnostic work-up of food allergy. Objective To evaluate the diagnostic capacity of the SPT in predicting the outcome of oral food challenges, and to determine decision points for the weal size and the skin index (SI) that could render double-blind, placebo-controlled food challenges unnecessary.


METHODS
In 385 children (median age 22 months), 735 controlled oral challenges were performed with cow's milk (CM), hen's egg (HE), wheat and soy. Three hundred and thirty-six of 385 (87%) children suffered from atopic dermatitis. SPT was performed in all children. Diagnostic capacity, receiver-operator characteristics (ROC) curves and predictive decision points were calculated for the mean weal size and the calculated SI.


RESULTS
Three hundred and twelve of 735 (43%) oral food challenges were assessed to be positive. Calculation of 95% and 99% predicted probabilities using logistic regression revealed predictive decision points of 13.0 and 17.8 mm for HE, and 12.5 and 17.3 mm for CM, respectively. However, using the SI, the corresponding cut-off levels were 2.6 and 3.7, respectively, for HE, and 2.7 and 3.7 for CM. For wheat, 95% and 99% decision points of 2.2 and 3.0 were found in children below 1 year of age.


CONCLUSIONS
Predictive decision points for a positive outcome of food challenges can be calculated for HE and CM using weal size and SI. They may help to avoid oral food challenges.
Verstege
A
A
Department of Pediatric Pneumology and Immunology, University Children's Hospital Charité of Humboldt University, Augustenburger Platz 1, 13353 Berlin, Germany.
Mehl
A
A
Rolinck-Werninghaus
C
C
Staden
U
U
Nocon
M
M
Beyer
K
K
Niggemann
B
B
D000284:Administration, Oral; D000293:Adolescent; D000485:Allergens; D000818:Animals; D002645:Chickens; D002648:Child; D002675:Child, Preschool; D003876:Dermatitis, Atopic / Q000276:immunology / Q000473:pathology; D004311:Double-Blind Method; D004531:Eggs; D005260:Female; D005512:Food Hypersensitivity / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D008892:Milk; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D012867:Skin / Q000473:pathology*; D012882:Skin Tests; D013025:Glycine max; D014908:Triticum
D000485:Allergens