Duotip-Test® II

BACKGROUND: Allergen skin prick testing remains an essential tool for diagnosing atopic disease and guiding
treatment. Sensitivity needs to be defined for newly introduced devices.
OBJECTIVE: Our aim was to compare the performance of 10 current allergy skin prick test devices. 
METHODS: Single- and multiheaded skin test devices (n [ 10) were applied by a single operator in a prospective randomized manner. Histamine (1 and 6 mg/mL) and control diluent were introduced at 6 randomized locations onto the upper and lower arms of healthy subjects. Wheal and flare reactions were measured independently by 2 masked technicians.
RESULTS: Twenty-four subjects provided consent, and 768 skin tests were placed. Mean wheal diameter among devices differed from 3.0 mm (ComforTen; Hollister-Stier, Spokane, Wash) to 6.8 mm (UniTest PC; Lincoln Diagnostics, Decatur, Ill) using 1 mg/mL histamine (P < .001) and 4.8 mm (GREER Pick; Greer, Lenoir, NC) to 8.4 mm (Duotip-Test II; Lincoln Diagnostics, Decatur, Ill; and Sharp-Test; Panatrex, Placentia, Calif) using 6 mg/mL histamine (P < .001). The false-negative rates ranged from 0% to 45% with 1 mg/mL histamine. The analytical specificity was 100% for all devices tested. All devices were well tolerated, with average pain score of less than 4 on a 10-point visual analog scale. Pain scores were higher among women, but this did not reach statistical significance. The Multi-Test PC and the UniTest PC had the lowest pain scores compared with the other devices.
CONCLUSIONS: All 10 skin prick test devices displayed good analytical sensitivity and specificity; however, 3 mm cannot arbitrarily be used as a positive threshold. The use of histamine at 1 mg/mL is unacceptable for certain devices but may be preferable for the most sensitive devices. On average, there was no pain score difference between multiheaded and single-head devices.