Comparison of the Multi-Test II and Skintestor Omni allergy skin test devices

Different devices for percutaneous allergy skin testing have demonstrated statistically and clinically significant differences in performance characteristics.

To compare 2 Food and Drug Administration-approved multihead allergy skin testing devices: Multi-Test II (Lincoln Diagnostics) and Skintestor Omni (Greer Laboratories).

Skin tests with glycerinated histamine (6-mg/mL base) and glycerinated saline were applied to 31 adults using Multi-Test II on the volar surface of one forearm and Skintestor Omni on the opposite forearm.

Data were accumulated from 155 histamine sites and 93 negative control sites for each device. Using cutoff wheal sizes of 5 vs 3 mm inclusive to define a positive result, Multi-Test II sensitivity remained at 100%, but specificity increased from 74% to 97%, whereas Skintestor Omni sensitivity decreased from 94% to 87%, and specificity increased from 58% to 88%. For Multi-Test II vs Skintestor Omni, histamine mean (SD) wheal sizes were 9.23 (1.37) vs 7.74 (2.83) mm (P < .001), mean coefficients of variance were 14.8% vs 36.6%, and pooled estimates of variance were 0.642 vs 6.974. Multi-Test II produced similar histamine wheal sizes regardless of test head position used, whereas Skintestor Omni produced statistically significantly smaller wheals at certain test head positions.

Multi-Test II had higher sensitivity and specificity than Skintestor Omni and produced reproducible wheal sizes from all test head positions. Because some Skintestor Omni test head positions produced significantly smaller histamine wheal sizes, skin testing using this device might result in underdiagnosis of allergy.