Background: Duplicate skin prick testing has previously been recommended because of reports that accidental negative tests are common. However, duplicate tests also mean an extra allergen load, which may increase the risk of inducing a generalized reaction at the test situation, at least in the youngest infants.
Objective: To investigate whether the occurrence of both a positive and negative test result is a common feature when performing duplicate skin prick tests and can therefore justify the duplicate method.
Methods: A retrospective analysis of all skin prick tests performed in duplicate at the pediatric clinic at University Hospital in Linköping, Sweden, in 1997.
Results: Of 1,087 skin prick tests, 14 resulted in one positive and one negative test, or 1.3%. The corresponding figure in the youngest age group, (ie, <2 years of age) was 3 of 340 (0.9%).
Conclusions: Considering the risk of inducing a summation of the reactions, and thereby a generalized allergic reaction, when applying an extra allergen load on the limited surface of the small arm, we conclude that the results of this study justify using single prick test, at least in the youngest age group and probably when testing children of all ages.