UniTest® PC

Abstract

Background: Curcumin has been shown to decrease allergic symptoms and biomarkers in some animal and human studies.

Objective: Our study aimed to determine if curcumin affects immediate skin-prick testing.

Methods: We enrolled 34 participants sensitized to select antigens. The participants were randomized to treatment with curcumin or placebo in a double-blind fashion. The participants underwent titrated skin-prick testing before and after 1 week of treatment and the pre- and posttreatment skin test wheals and flares were compared.

Results: Curcumin did not have a statistically significant effect on immediate skin-prick test wheal or flare size.

Conclusion: Although curcumin may attenuate allergic symptoms and biomarkers, it does not have a significant effect on immediate skin-prick test results and does not need to be discontinued before testing.

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.

"Utilizing the three skin testing devices, twenty subjects were tested on the back, four sites with histamine and four sites with saline. Greer Pick produced 52% greater intrasubject variability than UniTest PC, and 46% greater than the smallpox needle. Wheals greater than 3mm at saline sites occurred only from Greer Pick. Neither UniTest PC nor the smallpox needle produced wheals greater than 3 mm at saline sites. The highest sensitivity (100%) was gained from UniTest PC, While the lowest resulted from the smallpox needle (91%). Pain was minimal for all devices, but Greer Pick and the smallpox needle caused sharp pain while UniTest PC created a pressure-like pain. UniTest PC was considered, by the technicians, the easiest to use. Testing technicians observed that periodically a Greer Pick point did not penetrate the epidermis, necessitating repeat pricking."

Here are findings from the published work:

• Utilizing the three skin testing devices, twenty subjects were tested on the back, four sites with histamine and four sites with saline.
• Greer Pick produced 52% greater intrasubject variability than UniTest PC, and 46% greater than the smallpox needle.
• Wheals greater than 3 mm at saline sites occurred only from Greer Pick. There was no whealing greater than 3 mm at saline sites from either UniTest PC or the smallpox needle.
• The highest sensitivity (100%) was gained from UniTest PC while the lowest resulted from the smallpox needle (91%).
• Perception of pain was minimal for all three devices, but Greer Pick and the smallpox needle caused sharp pain while UniTest PC created a pressure-like pain.
• Technicians performing the skin tests considered UniTest PC the easiest to use of the three devices. They also observed that periodically a Greer Pick tine did not penetrate the epidermis, necessitating a repeat of the pricking.

In summary: UniTest PC was the only device that produced 100% sensitivity and 100% specificity. Pain from UniTest PC was defined as "pressure-like," while pain from Greer Pick and the smallpox needle was referred to as "sharp." Greer Pick produced 52% greater intrasubject variability than UniTest PC, and 46% greater than the smallpox needle. Technicians found UniTest PC easier to use than the other devices, and observed that periodically a Greer Pick point did not penetrate the epidermis, necessitating a repeat of the pricking.

Abstract

Background: Allergy skin test reliability depends on the reagents and controls selected. Histamine is used at 1mg/ml and 6mg/ml concentration but few studies address the rationale for selecting one versus the other and how this may impact diagnostic accuracy.

Objective: To determine the rate of false negative allergen skin tests responses between UniTest PC (using the 1mg/mL histamine) and Quintip devices (using 6mg/mL) for 4 common aeroallergens.

Methods: Subjects aged 18-65 with symptoms of allergy to cat and/or ragweed received skin testing with 4 aeroallergens (dust mite mix, timothy grass, ragweed, cat), histamine and control diluent. Those individuals who tested positive to cat or ragweed with one skin prick test (SPT) device but not the other then proceeded to nasal allergen challenge (NAC). The primary outcomes were the aeroallergen false negative rates and sensitivities of the skin test devices followed by nasal allergen (NAC).

Results: Twenty-five individuals were recruited and underwent a total of 300 SPTs. SPT to allergens (ragweed, dust mite, cat, and timothy grass) resulted in a statistically significant difference in wheal size among the two skin testing devices (p value <0.0001, 0.0001, 0.0006, and 0.0053 respectively). Six NAC procedures were performed to cat/ragweed and 5 of 6 (83% were positive). The overall allergen sensitivity rate for UniTest and Quintip were 97% and 78% respectively with most false negatives due to the use of 6mg/ml histamine control reagent.

Conclusion: Our study shows that 6mg/ml concentration of histamine control reagent may contribute to a false interpretation of aeroallergen skin prick test results.