EVALUATION OF DEVICES FOR SKIN PRICK TESTING

Background: Previous comparisons of devices for percutaneous skin test ing have revealed statistically and clinically significant differences , from one device to another, in the size of reactions to histamine an d allergen extracts and at negative control sites. Objective: The obje ctive of this study was to compare the performance of several skin tes t devices which are either new, modified, or used with a modified tech nique. Methods: Twenty subjects were tested five to eight times with e ach of the devices both to glycerol-saline and to 10 mg/ml histamine b ase. The devices tested were the MultiTest II, Duo Tip-Test (prick and scarification), Quintest, DermaPik (prick and scarification), and sma ll pox needle. Results: There were highly significant differences amon g the devices for the size of the reaction to histamine.(mean wheal di ameter 4.28 to 8.59 mm, p < 0.0001), the standard errors of the wheals to histamine (0.82 to 1.45 mm, p < 0.05) and in the mean wheal size w ith glycerol-saline (0.00 to 2.48 mm, p < 0.0001). Conclusions: Device s for performing skin prick testing vary greatly in several characteri stics, including the size of reactions at both positive and negative t est sites. Each skin test technician should be tested with the device used in that skin testing laboratory to establish criteria for positiv e and negative tests.