Evaluation of devices for skin prick testing.

BACKGROUND

Previous comparisons of devices for percutaneous skin testing have revealed statistically and clinically significant differences, from one device to another, in the size of reactions to histamine and allergen extracts and at negative control sites.

OBJECTIVE

The objective of this study was to compare the performance of several skin test devices which are either new, modified, or used with a modified technique.

METHODS

Twenty subjects were tested five to eight times with each of the devices both to glycerol-saline and to 10 mg/ml histamine base. The devices tested were the MultiTest II, Duo Tip-Test (prick and scarification), Quintest, DermaPik (prick and scarification), and small pox needle.

RESULTS

There were highly significant differences among the devices for the size of the reaction to histamine (mean wheal diameter 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 with glycerol-saline (0.00 to 2.48 mm, p < 0.0001).

CONCLUSIONS

Devices for performing skin prick testing vary greatly in several characteristics, including the size of reactions at both positive and negative test sites. Each skin test technician should be tested with the device used in that skin testing laboratory to establish criteria for positive and negative tests.