Reproducibility Of Patch Tests Research Articles

Patch testing with hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC)-a multicentre study of the Swedish Contact Dermatitis Research Group.

In 2014, the fragrance hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC) was excluded from the Swedish baseline series. To study (i) whether fragrance mix (FM) II with 5% HICC detects more positive reactions than usual FM II with 2.5% HICC, and (ii) the reproducibility of patch testing with HICC. Two thousand one hundred and eighteen dermatitis patients at five Swedish dermatology departments were consecutively tested with FM II 14% pet., FM II 16.5% pet., and duplicate preparations of HICC 5% pet. Of the patients, 3.2% reacted to FM II 14%, and 1.5% reacted to HICC. Separate testing with HICC detected 0.3% reactions without concomitant reactivity to FM II. FM II with 5% HICC did not give rise to more irritant reactions or signs of active sensitization than FM II with 2.5% HICC. Patch testing with duplicate applications of HICC increased the overall prevalence of HICC contact allergy to 1.9%. FM II with 5% HICC does not detect more positive reactions than FM II with 2.5% HICC. Separate testing with HICC does not detect a sufficient proportion of patients who react only to HICC, without concomitant reactions to FM II, to warrant its inclusion in a baseline series.

Allergic Contact Dermatitis from Corticosteroids: Reproducibility of Patch Testing and Correlation with Intradermal Testing

Corticosteroid contact allergy is not uncommon. The diagnosis can be made with either patch testing or intradermal (ID) testing. In view of a few problems that have been encountered with patch testing, patch testing is considered inferior to ID testing. The reported reproducibility of positive patch-test results in the literature ranges from 47 to 98%. This study was conducted to (1) determine the reproducibility of patch testing with topical steroid preparations and their clinical relevance, (2) correlate positive results with ID testing, (3) address the issue of cross-reactivity between different steroid groups, and (4) identify the percentage of positive reactions to preservatives and vehicles used in commercial topical steroids. A total of 19 patients with positive patch-test reactions to steroids from 1995 to 2004 were identified. Atopic patients and patients with type I hypersensitivity were excluded. The patients were patch-tested with a steroid series, select commercial steroid products, and vehicles and preservatives used in these preparations. The same patients were subjected to ID testing with select steroids. Readings were done on days 2, 5, and 7. ID testing was also performed on 9 control patients. Tixocortol-21-pivalate is the most common steroid allergen (68%). The reproducibility of patch testing with topical steroid preparations ranged from 66 to 100%. Reactions to both ID testing and patch testing occurred in 16 patients (89%); 1 patient reacted to patch testing and 1 other reacted to ID testing. Formaldehyde and formaldehyde releasers accounted for the majority of reactions in the vehicles and preservatives group. Patch testing is sufficient in diagnosing allergic contact dermatitis from topical steroids. Testing with commercial products is not a good screen for steroid allergy. The most common cross-reactions were between group A (hydrocortisone-type) corticosteroids and group D2 corticosteroids (composed of labile esters, with a long-chain ester at C17 and possibly C21).

The reproducibility of patch tests.

There is conflicting evidence regarding the reproducibility of patch testing. Discordant results have been reported in up to 44% of cases. The clinical relevance of these discordant patch tests has not been previously assessed. We studied 383 consecutive patients receiving simultaneous duplicate patch testing on opposite sides of the upper back with 10 allergens from the European standard series. Completely discordant patch tests-a negative test on one side with a positive test on the opposite side-were recorded in 30 (8%) patients. Two patients had discordant tests to two of the allergens; 28 had discordant reactions to one allergen. Completely discordant tests were recorded for nickel in 10 (3%) patients, balsam of Peru in two (0.5%), thiomersal in one (0.3%), cobalt in four (1%), paraphenylenediamine in three (0.8%), fragrance mix in two (0.5%), formaldehyde in four (1%), potassium dichromate in two (0.5%), lanolin in three (0.8%) and Kathon CG in one (0.3%). Of those patients with completely discordant patch tests, the allergen was deemed to be a true positive in 11 (3% of total) cases and of possible relevance in a further three. The allergen was felt to be relevant to the presenting complaint in seven (2% of total) patients.

Reproducibility of patch tests

The efficiency and reproducibility of patch tests remain controversial. Our purpose was to determine the efficiency and reproducibility of patch tests and to identify factors influencing these features. We double-tested 1285 patients concomitantly with 10 standard allergens by manually filled test chambers. Additional information was obtained from all patients with a standardized protocol. Patch test efficiency was good (> or = 0.94) with all 10 allergens. In contrast, nonreproducibility of patch tests was strongly allergen dependent, ranging from 0.2 for nickel sulfate to 0.6 for formaldehyde. The likelihood of nonreproducible allergic reactions increased when more than four positive reactions were seen at the same time, and with another positive reaction located in close proximity to an allergic reaction. Sex and age of patients, atopy, dermatitis at distant sites, sleeping habits, and the time of allergen exposure (24 or 48 hours) did not affect the rate of nonreproducible results. To increase patch test reproducibility, specific preparations of patch test allergens need to be improved. Furthermore, amplification effects by synchronous neighboring positive reactions should be excluded.

The role of vehicles in diagnostic patch testing

The correct selection of vehicles for patch testing is crucial in the evaluation of suspected allergic contact dermatitis. We reviewed the literature by using Grateful Med software for the years 1966-1992, utilizing the subjects "vehicles" and "allergic contact dermatitis" or "patch tests". Vehicles can influence bioavailability of the chemicals and subsequently percutaneous absorption or interaction with allergens. There are methodological problems in interpreting studies, such as sample size, percutaneous absorption and clinical aspects. Our judgement, partially validated by the literature, suggested that improved delivery systems (such as via vehicles) might significantly increase optimization, reliability and reproducibility of patch tests.

Reproducibility of Patch Tests: A United States Multicenter Study

The reproducibility of patch tests using allergens dispersed in petrolatum or water and placed into Finn chambers (Epitest Ltd, Oy, Hyryla, Finland) was studied in a double-blind fashion. A total of 128 patients were tested concomitantly to three different lots of an allergen to which they previously reacted positively and to one lot of the appropriate vehicle. The following allergens were evaluated with the total number of patients studied given in parentheses: benzocaine (10), mercaptobenzothiazole (9), cinnamic aldehyde (11), formaldehyde (14), nickel sulfate (15), quaternium-15 (15), neomycin (12), para-phenylenediamine (15), thiuram mix (14), and ethylenediamine dihydrochloride (13). Overall, the reproducibility of the triplicate responses among these patients was 88% (113/128). Reactions to benzocaine, mercaptobenzothiazole, thiuram mix, and nickel were reproducible in all patients. Reactions to cinnamic aldehyde (73%) and formaldehyde (79%) were the least reproducible. Eighteen percent (23/128) of patients failed to react to all of the allergen lots tested, suggesting “lost positive” reactions caused by either diminished sensitivity or a prior false-positive response. Among the allergies most likely to be lost were those for neomycin, formaldehyde, cinnamic aldehyde, thiuram mix, quaternium-15, and para-phenylenediamine. In contrast, reactions to benzocaine, nickel, mercaptobenzothiazole, and ethylenediamine were rarely lost. Failure to read the patch test sites later than 48 hours after application would result in a significant number of missed true-positive responses, especially for formaldehyde, quaternium-15, neomycin, and ethylenediamine dihydrochloride. These findings are discussed in light of prior published studies.

Reproducibility of Patch Tests: A United States Multicenter Study

The reproducibility of patch tests using allergens dispersed in petrolatum or water and placed into Finn chambers (Epitest Ltd, Oy, Hyryla, Finland) was studied in a double-blind fashion. A total of 128 patients were tested concomitantly to three different lots of an allergen to which they previously reacted positively and to one lot of the appropriate vehicle. The following allergens were evaluated with the total number of patients studied given in parentheses: benzocaine (10), mercaptobenzothiazole (9), cinnamic aldehyde (11), formaldehyde (14), nickel sulfate (15), quaternium-15 (15), neomycin (12), para-phenylenediamine (15), thiuram mix (14), and ethylenediamine dihydrochloride (13). Overall, the reproducibility of the triplicate responses among these patients was 88% (113/128). Reactions to benzocaine, mercaptobenzothiazole, thiuram mix, and nickel were reproducible in all patients. Reactions to cinnamic aldehyde (73%) and formaldehyde (79%) were the least reproducible. Eighteen percent (23/128) of patients failed to react to all of the allergen lots tested, suggesting “lost positive” reactions caused by either diminished sensitivity or a prior false-positive response. Among the allergies most likely to be lost were those for neomycin, formaldehyde, cinnamic aldehyde, thiuram mix, quaternium-15, and para-phenylenediamine. In contrast, reactions to benzocaine, nickel, mercaptobenzothiazole, and ethylenediamine were rarely lost. Failure to read the patch test sites later than 48 hours after application would result in a significant number of missed true-positive responses, especially for formaldehyde, quaternium-15, neomycin, and ethylenediamine dihydrochloride. These findings are discussed in light of prior published studies.

Reproducibility of patch tests

Patch tests with a series of 39 substances were performed in 41 patients on one side of the upper aspect of the back. Testing was repeated on the contralateral side of the back 1 week later (sequential testing). In 35 other patients, duplicate patch test series were simultaneously applied on both sides of the back (concomitant testing). If a positive reaction to a test substance was obtained at only one side of the back, the result was regarded as nonreproducible. Of all positive reactions, 40.0% were nonreproducible at sequential testing and 43.8% were nonreproducible at concomitant testing. Weakly positive reactions were far more often nonreproducible than stronger reactions.