Food allergy: Diagnosis and beyond
Available from: Anna Nopp
- "Thus the low correlation support that the reproducibility was poor for dose and severity score. Difficulties to determine allergen thresholds doses at food challenges have also been noted by others . This is in contrast to CD-sens where we did not find any significant differences but a significant and strong correlation between the two CD-sens occasions. "
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ABSTRACT: Double-blind placebo-controlled food challenge, DBPCFC, the gold standard for diagnosing food allergy, is time-consuming and potentially dangerous. A basophil allergen threshold sensitivity test, CD-sens, has shown promising results as a diagnostic tool in food allergy.
To evaluate the reproducibility of oral peanut challenge and compare the outcome to CD-sens in peanut-sensitized children.
Twenty-seven children (4-19 years) underwent a DBPCFC followed by a single-blind oral food-challenge. The peanut challenges (1 mg to 5 g) were evaluated by severity scoring. Blood samples were drawn for CD-sens before the two first challenges.
Thirteen children (48%) did not react at any of the challenges. Fourteen reacted at both peanut challenges but not to placebo. Only two of these children reacted at the same threshold dose and with the same severity score. All other children scored differently or reacted at different doses. For children with a positive challenge the geometric mean of the ratio of the doses was 1.834 (p = 0.307) and the arithmetic mean of the difference between the severity scores was 0.143 (p = 0.952). No association was obtained between the two peanut challenges regarding severity score (r(s) = 0.11, p = 0.71) or threshold dose (r(s) = 0.35, p = 0.22). Among the children positive in peanut challenge, 12 were positive in CD-sens. Two were low-responders and could not be evaluated. Geometric mean of the ratio of CD-sens values in children with a positive challenge was 1.035 (p = 0.505) but unlike for the severity score and the threshold dose the association between the two CD-sens values was strong (r(s) = 0.94, P<0.001).
For a positive/negative test the reproducibility is 100% for both peanut challenge and CD-sens. However, a comparison of the degree of allergen threshold sensitivity between the two tests is not possible since the threshold dose and severity scoring is not reproducible.
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ABSTRACT: In children with food allergy, multiple food-specific serum IgE levels to common food allergens are frequently measured.
To compare food-specific serum IgE measurements among common food allergens in children with food allergy to determine the characteristics of the measurements, their ability to discriminate between foods associated and not associated with a presenting clinical reaction, and their change over time.
A retrospective analysis was conducted of food-specific serum IgE to cow's milk, egg white and yolk, peanuts, almond, and soy, for up to 3 subsequent measurements, in 291 children with food allergy. A food-specific serum IgE level lower than 0.35 kU/L was considered a negative measurement. The correlation of IgE measurements with presenting symptoms was conducted for each food in 172 children.
Of 1,312 food-specific serum IgE measurements, 69.8% were positive. The median (interquartile range) IgE level for foods associated with the presenting complaint was 7.3 kU/L (2.7-31) and that for foods not associated with a clinical complaint was 2.2 kU/L (0.38-13). The difference was statistically significant (P = .01) only for cow's milk. Specific IgE levels were highest for peanuts, followed by cow's milk, eggs, soy, and almonds, and trended upward over time.
In children presenting with clinical symptoms of a reaction to a food allergen, measurements of food-specific serum IgE to other common food allergens are commonly positive. An increase in food-specific serum IgE occurs over time.
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