Reproducibility of skin tests. A comparative study of the Pepys prick test and the Morrow-Brown needle and their correlation with the serum IgE level.

Fifty patients allergic to mite were tested for D. pteronyssinus using two prick-test techniques; the classical method by Pepys and the Morrow-Brown needle. Each patient received six tests with each method on the two forearms. The evaluation of the weal areas was conducted in two ways: by weighing the shapes of the tests transferred on to paper, and by measuring the two greatest diameter lengths. No significant difference was observed between the two methods. No significant difference was observed between the measurements of the same tests carried out at 2-monthly intervals by the same examiner. With the Pepys method the weal area sizes are significantly larger than with the Morrow-Brown needle, and the variance is much greater with the Pepys technique. However, the coefficients of variation are similar and in both cases the techniques are equally reproducible. No significant difference was found in the weal sizes with regard to the injection sites on the forearm with either of the two methods. The correlation between the weal area sizes and the log of the IgE levels is closer with the Morrow-Brown needle.