The reproducibility of the allergy skin test scoring and interpretation by board-certified/board-eligible allergists

Background: Allergy skin testing is a cornerstone in the evaluation of the allergic patient. This seemingly simple test is subject to multiple variables that can affect the result. Objective: To evaluate the degree of variability among board-certified/board-eligible allergists in the scoring and interpretation of allergen skin tests. Materials and Methods: A series of allergen prick skin tests were digitally photographed and a questionnaire generated. Approximately 70 board-certified/board-eligible allergists were asked to grade each test item and to interpret them as positive, negative, or indeterminate or if they desired a followup intradermal test. Results: Thirty-three interpretable responses were obtained. The majority of respondents (24) used a grading scale of 0 to 4. Agreement among physicians using a 0 to 4+ scale ranged from a standard deviation of 0.26 to 1.35, with greatest agreement on items with median/mode scores of 4+. The largest standard deviations were found on test items with median/mode scores of 1 + to 2+. Interpretation of the test items also showed greatest variation for those items with median/mode scores of 1+ to 2+. The number of intradermal tests requested ranged from 0 to 11 (of 22 test items). Conclusions: The results demonstrate interphysician variation in the scoring and interpretation of epicutaneous skin tests. A questionnaire such as the one used here may serve a useful quality control instrument to ensure reproducible scoring of skin tests. In addition, the results highlight the need for greater study on the clinical utility of intradermal skin testing when epicutaneous tests are negative or equivocal.