Patch test

Abstract: Background: Allergic contact dermatitis is a significant cause of cutaneous disease affecting many individuals. Patch testing, when used properly, often provides support for the diagnosis of allergic contact dermatitis. Objective: This article reports patch testing results from July 1, 1994, to June 30, 1996, by the North American Contact Dermatitis Group (NACDG). Methods: Patients evaluated in our patch test clinics were tested with the same screening series of allergens by the use of a standardized patch testing technique. The data from these patients were recorded on a standard computer entry form and analyzed. Results: Forty-nine allergens were tested on 3120 patients. Budesonide was added to the series in July 1995 and tested on 1678 patients. Of these patients, 66.5% had positive allergic patch test reactions, and 57% had at least one allergic reaction that was felt to be clinically relevant to the present or past dermatitis. The 20 screening allergens commercially available to United States dermatologists in the Allergen Patch Test Kit, accounted for only 54.1% of the patients with positive allergic reactions. The additional 30 allergens on the NACDG screening series accounted for 47% of patients with positive allergic reactions. Had the Allergen Patch Test Kit alone been used, 12.4% of all patients tested may have had their disease misclassified as a nonallergic disorder, and an additional 34.4% of all tested patients would not have had their allergies fully defined. Among those patients with positive responses to the supplemental allergens, 81% of the responses were of present or past relevance. The 12 most frequent contact allergens were nickel sulfate, fragrance mix, thimerosal, quaternium-15, neomycin sulfate, formaldehyde, bacitracin, thiuram mix, balsam of Peru, cobalt chloride, para-phenylenediamine, and carba mix. The present relevance varied with the specific allergen from 10.7% (thimerosal) to 85.7% (quaternium-15). Among newer allergens, methyldibromoglutaronitrile/phenoxyethanol (cosmetic preservative) caused positive allergic reactions in 2% of the patients; tixocortol-21-pivalate and budesonide (corticosteroids), in 2.0% and 1.1% of the patients, respectively; and ethylene urea/melamine formaldehyde mix (textile resin), in 5% of the patients. Conclusion: The usefulness of patch testing is enhanced with the number of allergens tested, because allergens not found on the commercially available screening series in the United States frequently give relevant allergic reactions. (J Am Acad Dermatol 1998;38:911-8.)

Abstract: Background:Allergic contact dermatitis is a significant cause of cutaneous disease affecting many individuals in the home and at the workplace. Patch testing is the most worthwhile diagnostic tool for the evaluation of patients with suspected allergic contact dermatitis.Objective:This study reports

Abstract: Background Patch testing is an important diagnostic tool for the assessment of allergic contact dermatitis (ACD). Objective This study documents the North American Contact Dermatitis Group (NACDG) patch testing results from January 1, 2015, to February 28, 2017. Methods At 13 centers in North America, patients were tested in a standardized manner with a screening series of 70 allergens. Data were manually verified and entered into a central database. Descriptive frequencies were calculated, and trends were analyzed using χ test. Results A total of 5597 patients were tested. There were 3725 patients (66.6%) who had at least 1 positive reaction, and 2798 patients (50.2%) were ultimately determined to have a primary diagnosis of ACD. A total of 572 patients (10.2%) had occupationally related skin disease. There were 10,983 positive allergic reactions. Nickel remained the most commonly detected allergen (17.5%). Methylisothiazolinone, which was added to the screening series for the 2013-2014 cycle, had the second highest positive reaction rate of allergens tested (13.4%). Compared with the previous reporting periods (2013-2014) and (2005-2014), positive reaction rates for the top 35 screening allergens statistically increased for only 1 allergen: hydroxyethyl methacrylate (3.4%; risk ratios, 1.24 [confidence interval, 1.00-1.54] and 1.46 [confidence interval, 1.23-1.73]). Three newly added allergen preparations-ammonium persulfate (1.7%), chlorhexidine (0.8%), and hydroquinone (0.3%)-all had a reaction rate of less than 2%. Twenty-three percent of the tested patients had at least 1 relevant allergic reaction to an allergen not on the NACDG series; 12% of these were occupationally related. T.R.U.E. Test (SmartPractice Denmark, Hillerod, Denmark) would have hypothetically missed one quarter to almost 40% of reactions detected by the NACDG screening series. Conclusions These results confirm that the epidemic of sensitivity to methylisothiazolinone has continued in North America. Patch testing with allergens beyond a screening tray is necessary for a complete evaluation of occupational and nonoccupational ACD.

Abstract: Repeated open application tests (ROATs) were performed with common ingredients of vehicles in 86 patients with contact dermatitis. The substances were applied twice daily for 7 days to the flexor aspect of the forearm near the cubital fossa, unless dermatitis appeared earlier. Of the patients with a questionable (?+) patch test result, 44% were positive in ROATs. The corresponding figure was 80% in the patients with a positive (+ or ++) response in the patch test, when the results of ROAT with propylene glycol were excluded. Only 5 of 14 patients reacting to 30% or to 10% propylene glycol but not to 1% in water in patch testing, showed a positive result to a cream containing 5% propylene glycol in ROAT. All 5 patients with a positive patch test reaction to 1% propylene glycol reacted to 5% propylene glycol in ROAT. The results suggest that ROATs should be performed more often, especially in patients in whom little known or new allergens are suspected as being the cause of allergic contact dermatitis.