Comparison of two disposable plastic skin test devices with the bifurcated needle for epicutaneous allergy testing

The Greer DermaPIK and the Lincoln Diagnostics Duotip-Test are frequently used plastic, disposable, allergy skin testing devices.

To compare the prick method of using the bifurcated needle and DermaPIK with the Duotip-Test using both the scratch (rotation) and prick methods for sensitivity, precision, and level of discomfort.

Skin-testing was done with histamine and saline on the back in triplicate on 24 volunteers (mean age 32.8, seven males). Wheal and erythema were measured and a photograph was taken. Discomfort was rated on an analog scale.

The bifurcated needle and the Duotip-Test prick technique had significantly smaller histamine wheal and erythema responses than either the DermaPIK prick or Duotip-Test scratch techniques (P < .05). The Duotip-Test scratch produced significantly larger wheals (mean 1.1 mm, P < .001) to saline than the other three methods. Erythema to saline by Duotip-Test scratch (mean 3.16 mm) was significantly larger than the bifurcated needle (mean 1.2 mm, P < .001) and Duotip-Test prick method (mean 1.6 mm, P < .01). There was no statistical difference in the histamine coefficient of variation among the four methods. The Duotip-Test scratch method was rated significantly higher in patient discomfort (mean 21.6, P < .05) than the bifurcated needle (mean 7.8). No differences in discomfort were noted between the other methods.

The Duotip-Test scratch method had the largest mean wheal/erythema to histamine and the lowest CV. It had the most dermatographism and was more uncomfortable than the other methods. The other devices and methods were very similar in response to histamine and saline, and to precision and discomfort.