Long-lasting allergic patch test reactions: a study of patients with positive standard patch tests

The purpose of this study was to determine the duration of patch test reactions and the frequency of long-lasting allergic patch test reactions (LLAPTR), and to identify the possible factors related to the development of the LLAPTR. For this purpose, a group of 263 patients positive to 1 or more allergens in the GIRDCA standard series was recruited. Readings were made for each patient 2 and 3 days after patch test application and continued every 2nd and 3rd day until the disappearance of all palpable erythema. The % of LLAPTR out of the total of reactions was high: 17.9%). Kathon CG was the hapten that caused LLAPTR most frequently, with 16 cases, a frequency of 76.1%), and a mean duration of the patch test reactions of 25.4 days. Risk factors investigated were age, sex, atopy, intensity of the patch test reaction and sensitivity to some allergens with the greatest number of positive patch tests. The relative importance of each risk factor was calculated by multivariate stepwise logistic regression analysis. It was found that a Kathon CG sensitivity was the most important risk factor for LLAPTR. 2nd was atopy, followed by strong patch test reaction. Rejected risk factors were sex, age and sensitivity to nickel sulfate, potassium dichromate, Disperse Blue 124, fragrance mix and p-phenylenediamine.     

Contact allergy in chronic leg ulcers: results of a multicentre study carried out in 423 patients and proposal for an updated series of patch tests

Background:  There is a lack of prospective studies investigating contact sensitization in patients with chronic leg ulcers.
Objectives:  To determine the frequency of contact sensitization in patients with chronic leg ulcers using a special series of patch tests and to determine whether the number of sensitizations was correlated with the duration of the chronic leg ulcers.
Patients/methods:  Multicentre study carried out in patients with chronic leg ulcers; patch tests with the European baseline series and with an additional 34 individual allergens or mixes and 3 commercial products.
Results:  Of the 423 patients (301 women, 122 men, mean age 68.5 years) with chronic leg ulcers, 308 (73%) had at least one positive patch test with 3.65 positive patch tests per patient. The main allergens were Myroxylon pereirae (41%), fragrance mix I (26.5%), antiseptics (20%), and corticosteroids (8%). The number of positive tests per patient was not correlated with the cause of ulcer but was increased with the duration of the ulcer with a statistical difference between the group of the <1 year compared with the group >10 years duration.
Conclusions:  From this large prospective multicentre study, polysensitization is frequent in patients with chronic leg ulcers, increasing with the duration of the ulcer. We propose avoidance of topical antiseptics and ointments containing perfumes in patients with chronic leg ulcers and an updated patch test series for investigating these patients.     

Allergic contact dermatitis in venous leg ulcer patients

Our aim was to determine the frequency and nature of contact sensitivity in venous leg ulcer patients in Lanarkshire. We performed patch testing with the European standard series, antimicrobials and medicaments on 200 patients referred to our leg ulcer clinics. Positive patch tests were found in 136 (68%) patients. Multiple allergies occurred in 102 (51%). The most frequent allergen groups were fragrances (30.5%), antimicrobials (19.5%), topical excipients (19.5%), rubber accelerators (13.5%) and topical corticosteroids (8%). We also found a high prevalence of positive patch tests to Intrasite gel (9.5%) and Hioxyl cream (8.5%), medicaments which are commonly used to treat leg ulcers in our area. Contact sensitivity is common in venous leg ulcer patients and has important implications for patient management. The allergens involved vary depending on local nursing practice. We suggest that all venous leg ulcer patients be patch tested with a locally relevant patch test series.     

Measurement of risk of sensitisation and its application to Kathon

The prevalences of patch test reactions to 27 common allergens including Kathon 100 ppm, were calculated in a standard test battery applied to 2 consecutive cohorts of 656 and 653 patients seen in 1985/6 and 1986/7. The overall prevalence of Kathon sensitivity was 0.9% for 1985-87. The prevalence for 1985/6 and 1986/7 was 0.8% and 1.1% (difference not significant). The rate of sensitisation to Kathon was measured in 212 patients with negative patch tests by retesting after 6-15 months (mean 10.8 months +/- 0.2 SE), and gave a mean rate of sensitisation of 1/2280 patient months or 0.5%/patient population. Retesting 45 negative reactors after 4 weeks gave no new reactors, showing that the rate of sensitisation by patch testing with 100 ppm Kathon is low. It is concluded that the low and stable prevalence of Kathon sensitivity and the low rate of new sensitisation is in keeping with a low potential for sensitisation. Used on a larger scale, the present method would rapidly define risk from potential new allergens.     

Delayed patch test reactions at days 7 and 9

403 consecutive patients were examined on days 2, 4, 7, and 9 following application of patch tests. Late positive reactions, i.e., those which manifested after day 4, were seen in 29 patients (7.2%). The allergens which most commonly produced late positive reactions were neomycin (7), potassium dichromate (4), and cobalt (3). Paired patch test readings on days 4 and 7 were more reliable than those on days 2 and 4. If only 1 patch test reading were performed, a single reading on day 4 would have been most useful. The reading on day 9 proved to be of limited value. Of 11 patients who were retested after an interval of more than 6 months, 7 showed earlier eliciting reactions, which may have been due to active sensitization.     

Prevalence and sources of sensitization to emulsifiers: a clinical study

737 patients with suspected cosmetic- or medicament-related contact dermatitis were patch tested with 6 emulsifier agents: triethanolamine, cetyl stearyl alcohol, sorbitan sesquioleate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monooleate, and Amerchol L 101. 39 patients (5.3%) gave 1 or more positive patch tests to emulsifiers. A total of 54 positive reactions were found, 23 of which were clinically relevant, triethanolamine being the most frequent sensitizer. Patients with emulsifier sensitivity generally give a high prevalence of positive patch tests to other common ingredients of topical preparations, such as preservatives or active ingredients. Cosmetics and topical medicaments were detected as the source of sensitization in an equal number of patients. Patch tests with patients' own causative preparations were frequently negative. To avoid overlooking emulsifier sensitivity, it is advisable to test these compounds in patients with contact dermatitis that is possibly due to topical preparations, regardless of whether they have other clinically relevant positive reactions or whether patch tests with their own products are negative.     

P34Reproducibility of the positive patch test reactions with the TRUE Test

The patch test results of patients tested at least twice at our clinic during a period of 11 years were analyzed with regard to reproducibility of the positive patch test reactions found in the first patch testing session.
A retrospective analysis of 257 patients who have been tested with the TRUE Test at least twice between 1991 and 2002 and had a minimum of one positive reaction in the first testing session was done. Test reactions were read routinely after 3 and 5–7 days.
In the first testing session a total of 299 positive reactions were found. Of these allergens, 151 (51%) stayed positive in the second test, 31 (10%) produced a doubtful reaction, 67 (22%) a negative response, and 50 (17%) were not retested because of strong positive reactions in the first test. Of the individual allergens, positive reactions from thiuram‐mix, kathon CG and colophony were the most reproducible.
If it is assumed that allergens which were not retested because of strong positive reactions would have shown positive reactions in a retest, a total of 68% of positive reactions were reproduced. A multitude of factors, such as: avoidance of relevant allergens between tests, diminished sensitivity, retesting within a period of more or less active dermatitis, different observers, methodological error, and prior false‐positive responses, influence the reproducibility of patch tests. The results will be put in perspective.     

A retrospective study of patch tests in Chongqing, China from 2004 to 2009

Background. There has been no previous report on allergens responsible for dermatitis in southwest China. Objective. To investigate the prevalence of contact allergy in southwest China, we retrospectively analysed the patch testing results in our department from 2004 to 2009. Methods. A total of 2758 patients were patch tested with the Chinese baseline series of contact allergens (Beijing Medical University), the most common baseline series used in China. The results from patch tests were collected, analysed, and compared with clinical findings. Results. Of 2758 patients tested, 1826 (66.2%) were allergic to one or more common allergens. Five hundred (27.4%) patients had more than two contact allergies. One patient showed positive reactions to seven allergens. The most common allergens among the 1826 patients with positive reactions were nickel sulfate (39.5%), potassium dichromate (13.5%), thiomersal (11.6%), fragrance mix (6.9%), and rubber mix IV (5.8%). Nickel sensitivity was more common in female patients, and potassium dichromate sensitivity was more common in male patients (p < 0.001). Conclusion. Contact allergy in southwest China has particular characteristics, and these findings should be helpful in the development of strategies to reduce contact allergy in this geographical region.     

Contact sensitivity in patients with venous leg ulcers in Serbia: comparison with contact dermatitis patients and relationship to ulcer duration

Background: Contact hypersensitivity is a common occurrence in patients with chronic venous leg ulcers (CVLU) with allergen profiles depending upon the local treatment policies.
Objective: This study was to determine the frequency of contact sensitivity, prevalence of individual allergens, polyvalent sensitization, and/or their relationship to ulcers duration in the population of CVLU and contact dermatitis patients in Serbia.
Patients: 75 patients with CVLU and 82 patients with clinically suspected contact dermatitis were prospectively included in the study. The patients were patch tested with a series of 21 standard and 22 supplemental allergens.
Results: 73% ( n  = 55) of CVLU and 52% ( n  = 43) of control subjects had 1 or more positive patch test results ( P  < 0.01). Polysensitization was found in 53% of patients and 21% of controls ( P  < 0.01). CVLU patients run 2.5 and 4.3 higher risk for contact sensitization and polysensitization, respectively. The most common allergens were Balsam of Peru (21.3%), carba mix (18.7%), fusidic acid (17.3%), colophony (13.3%), paraben mix (12%), chloramphenicol (12%), silver nitrate (12%), and neomycin (10.7%). Polivalent sensitization and higher mean number of allergens were associated with ulcer duration >5 years.
Conclusions: The results confirm a high rate of contact (poly)sensitization in patients with CVLU and local variability in allergen prevalence.     

Screening for acrylate/methacrylate allergy in the baseline series: our experience in Sweden and Singapore

Background: No studies to specifically determine the prevalence of contact allergy to acrylates/methacrylates in patch tested populations have been published. Objectives: To determine the prevalence of acrylate/methacrylate allergy in all patients tested to the baseline patch test series. Methods: Five acrylate/methacrylate allergens (2‐hydroxyethyl methacrylate, methyl methacrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate, and 2‐hydroxypropyl acrylate) were included in the baseline series for at least 2 years in Malmö and Singapore. Results: Thirty‐eight patients in total had reacted to acrylate/methacrylate allergens in the baseline series during the study period in both populations. In Malmö, there were 26 (1.4%) patients with positive patch tests to acrylate/methacrylate allergens, 14 of whom had relevant reactions. In Singapore, there were 12 (1.0%) patients with positive patch tests to acrylate/methacrylate allergens, but only 1 had relevant reactions. If we had not added acrylate/methacrylate allergens to the baseline series, we would not have patch tested 13/26 (50%) of the positive reactors in Malmö and 11/12 (92%) of the positive reactors in Singapore. The overall proportion of missed positive reactors would have been 24/38 (63%). Conclusions: The prevalence of acrylate/methacrylate allergy in our patch tested dermatitis populations is 1.4% in Malmö and 1.0% in Singapore.     

Prevalence of delayed hypersensitivity to the European standard series in a self-selected population

There are limited reports of the prevalence of positive reactions in healthy adults to patch tests with standard allergens; there are no recent comprehensive studies from Australia. Healthy adult volunteers (n = 219) from the Western Australian community were patch tested using the European standard series of allergens. Seventy-seven (35%) reacted to at least one allergen, positive patch tests being most prevalent to nickel sulfate (20%), potassium dichromate (9%), cobalt chloride (6%) and fragrance mix (4%). Prevalence of positive patch tests to nickel and chromate was higher than that reported for another healthy population, which may stem from self-selection of volunteers or geographical differences, including extent of exposure to allergens.     

Allergic contact dermatitis in hairdressers: frequency and source of sensitisation

Occupational skin diseases are very common among hairdressers. The aim of our study was to evaluate the frequency, the age distribution and the source of contact sensitization in a group of 209 hairdressers who consulted our Clinic from 1990 to 1999. One hundred and thirty-two patients showed one or more clinically relevant positive reactions to different allergens; 89 of them were positive to the hairdressers' series and 43 were positive to other allergens. Para-phenylenediamine base and para-toluenediamine sulphate caused the greatest number of positive reactions (77 and 29 respectively). Both glyceryl monothioglycolate and ammonium persulphate gave 25 positive patch tests. The allergens not included in the hairdressers' series which gave the greatest number of positive reactions were nickel sulphate and disperse dyes yellow 3, blue 124 and red 1. The allergens known as strong skin sensitizers have remained almost the same over the years. Preventive measures should be mandatory to protect hands and to improve the safety of this job.     

Simultaneous sodium lauryl sulphate testing improves the diagnostic validity of allergic patch tests. Results from a prospective multicentre study of the German Contact Dermatitis Research Group (Deutsche Kontaktallergie-Gruppe, DKG)

Background There is evidence that a higher skin susceptibility may induce nonspecific erythematous or weak positive reactions to contact allergens in patch testing. Objectives To evaluate whether simultaneous application of sodium lauryl sulphate (SLS) along with diagnostic patch tests with contact allergens can provide information regarding skin irritability which may help to discriminate allergic from nonspecific irritant reactions to contact allergens. Methods Between July 2001 and June 2003, this prospective study collected patch test data of 5971 patients from 19 centres in Germany and Austria in the Information Network of Departments of Dermatology (IVDK). In addition to contact allergens (standard series and eight known ‘problematic’ allergens with a low reaction index and a high positivity ratio: 1,3‐diphenylguanidine, amerchol L‐101, benzalkonium chloride, benzoyl peroxide, cocamidopropyl betaine, octyl gallate, phenyl mercuric acetate and propylene glycol), patches with SLS 0·5% and 0·25% aq. were applied. Reactions to the allergens and to SLS were analysed at the IVDK data centre. The association between an erythematous or positive reaction to a certain allergen and an irritant reaction to SLS was assessed with logistic regression analysis, at the same time controlling for the influence of age and sex. Results Of the 29 allergens of the standard series, 23 and 21 gave a higher percentage of nonspecific erythematous reactions in patients with an irritant reaction to 0·25% and 0·5% SLS, respectively, in comparison with SLS‐negative patients. All eight ‘problematic’ allergens gave an increased percentage of nonspecific erythematous reactions. Similarly, 22 and 21 allergens of the standard series gave a higher percentage of positive allergic reactions in patients with an irritant reaction to 0·25% and 0·5% SLS, respectively, and seven of the eight ‘problematic’ allergens gave a higher percentage of positive allergic rections (exception: octyl gallate). For most allergens, the markers of skin reaction (reaction index and positivity ratio) were worse in SLS‐positive patients. Differences were more pronounced when testing with SLS 0·25% than with SLS 0·5%. Conclusions Because there is a convincing association between skin irritability (evaluated by SLS test) and the degree of skin reaction to contact allergens, the SLS test may help in deciding whether a doubtful erythematous or weakly ‘positive’ skin reaction should be interpreted as allergic or irritant.     

Statistical evaluation of the persistence of acquired hypersensitivity by standardized patch tests

Numerous studies have focused attention on the influence of various biological and environmental factors on contact hypersensitivity. In order to evaluate the persistence and/or modification of allergic contact sensitivity 10 a number of common contact sensitizers, the same standardized patch tests were repeated on 174 subjects with contact sensitivity after a lime lapse of 5 years (1987–1992). In 18.4% of the cases, 1 or more sensitivities were lost: 28.7% of the patients had a higher number of positive patch tests after 5 years, while the remaining 52.9% of the patients showed no change in the number of positive patch tests. In 88%, the positive allergens were unchanged, whereas in the remaining 12% of the subjects, they showed 1 or more variations. The association between the allergens most often positive was calculated for both the 1st and the 2nd patch lest results. Moreover, to evaluate the frequency of an allergen's positivity. We studied the disappearance of old sensitivities and the appearance of new sensitivities by the McNemar test. Cobalt chloride was the only allergen with a significant frequency of new positivities over the period of observation ( p < 0.01). Logistic regression analysis was performed to evaluate the possible influence of positive tests to other allergens, and of some clinical findings associated with contact dermatitis, on the sensitivity to cobalt chloride in 1987 and in 1992.     

Patch testing by additional series of allergens: results of further experiences.

BACKGROUND: Patch testing with additional series (AS) of allergens may be a useful tool in diagnosing allergic contact dermatitis (ACD). OBJECTIVE: Aim of the study was to verify the usefulness, to check the reliability in clinical practice and to evaluate the economic costs of AS previously built up. METHODS: A total of 281 patients with suspicious ACD underwent patch test with the standard series (SS) and with one or more AS (51 among 71 built up). RESULTS: A total of 170 patients (60.5%) showed positive reactions to SS; 116 (41.3%) to AS. Among 582 nonstandard allergens used, 113 (19.4%) elicited 1 or more positive reactions: out of 10,916 patch tests carried out, 260 (2.4%) positive reactions were observed. The correlation between SS and AS indicated that 8.2% patients resulted SS-/AS+, 27.7% SS+/AS-, 32.7% SS+/AS+, 31.3% SS-/AS-. The most frequently used AS showed the following percentages of patients with 1 or more positive reactions: clothes 41.4%, building industry 51.8%, hairdressers 77.3%, textile industry 42.1%, shoes 36.8%. Positive reactions to the most frequently used nonstandard allergens resulted: propylene glycol 0.4%, cobalt chloride 12.6%, phenylmercuric nitrate 2.2%, p-aminophenol 4.5%. The approximate economic cost of patch testing with AS has been evaluated in 1.3 euro per single patch test. CONCLUSION: The cost of patch testing AS is not irrelevant, but it can be compensated by the advantages deriving from the increase of data concerning ACD etiology. A reduction in the number of allergens included in single AS should be performed. Cobalt chloride, taking into account the high percentage of positive reactions observed and its presence in a large number of AS, could be (re)introduced in the standard series.     

Contact dermatitis with negative patch tests: the additive effect of allergens in combination

We deduced on theoretical grounds that conventional patch testing would be inadequate for the detection of sensitivity to multiple allergens. Fourteen patients with positive patch tests to two unrelated allergens were studied and the response to those two allergens was measured when tested singly or in combination, using 10 different pair combinations from 15 common allergens. With serial dilutions in chloroform (14 patients) and paraffin (four patients), the response was related to the log-dose of the allergen, and change in skin-fold thickness corresponded well with clinical grading. Single allergens diluted below the threshold for a patch-test response gave a response when given in combination, the threshold for a response to one allergen being lowered by the presence of another. On the linear part of the dose-response curves the response to the mixture of allergens was additive, the combined response being the sum of the individual components. Approaching the plateau region the response to the combination was greater than to the individual allergens but less than the sum of the single responses. The same results were obtained with allergens in paraffin. We conclude that conventional single allergen patch testing by itself is inadequate for the diagnosis of contact dermatitis.     

Patch testing with a combination of unrelated allergens: a new strategy

Summary A simplified method of patch testing was designed, in which several totally unrelated allergens were combined in each patch. The method was evaluated by double blind comparison of responses to 17 standard allergens applied individually as 17 conventional patch tests, and as two different sets of five patches each containing combinations of three or four allergens per patch, in 137 patients under investigation for contact allergic dermatitis. There were 89 positive responses to conventional patch testing with separate allergens and 94 and 86 positives to the two different combinations of the same allergens. Concordance of positive reactions to the two combinations was 80% and there were no irritant reactions. Conventional testing detected 70 and 74% of reactions to combination patches 1 and 2 and combination patches 1 and 2 detected 80 and 79% of the reactions to conventional testing. The combinations detected clinically relevant sensitivities not found by conventional testing. Thus, combination patch testing appears to give consistent and reliable results; its use would reduce the number of patches and increase the diagnostic yield for the specialist and permit preliminary screening by the general practitioner.     

Positive patch tests with a dermatophagoides mix relate to an increased responsiveness to standard patch test allergens

The diagnostic meaningfulness of patch tests with house dust mite allergens is still questionable. Our own impression has been that positive results with a dermatophagoides mix may occur preferentially in patients with a generally enhanced responsiveness to contact allergens. To check this, all of our patients allocated to patch testing with the standard series were additionally patch tested with a dermatophagoides mix by the same technique that was used for standard contact allergens. Out of 571 patients tested, 188 showed delayed responses to this mix that were indistinguishable from typical allergic patch test reactions but of no apparent clinical relevance. No relationship was found between positive dermatophagoides patch tests and an atopic disposition of the patients or characteristics of their eczema. However, 64.4% of the patients with a positive dermatophagoides patch test showed a response to at least 1 contact allergen of the standard series, compared to only 56.4% of the patients without a positive dermatophagoides reaction (p < 0.05). The reactivity to the mite mix was not related to the responsiveness towards any particular contact allergens. We suppose that some unidentified factors may contribute to positive reactions to the dermatophagoides mix that may also favour an enhanced general responsiveness to contact allergens.     

Multicenter study of preservative sensitivity in patients with suspected cosmetic contact dermatitis in Korea

As many new cosmetic products are introduced into the market, attention must be given to contact dermatitis, which is commonly caused by cosmetics. We investigate the prevalence of preservative allergy in 584 patients with suspected cosmetic contact dermatitis at 11 different hospitals. From January 2010 to March 2011, 584 patients at 11 hospital dermatology departments presented with cosmetic contact dermatitis symptoms. These patients were patch-tested for preservative allergens. An irritancy patch test performed on 30 control subjects using allergens of various concentrations showed high irritancy rates. Preservative hypersensitivity was detected in 41.1% of patients. Allergens with the highest positive test rates were benzalkonium chloride (12.1%), thimerosal (9.9%) and methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) (5.5%). Benzalkonium chloride and chlorphenesin had the highest irritancy rate based on an irritancy patch test performed using various concentrations. Seven of 30 normal subjects had a positive irritant patch reading with 0.1% benzalkonium chloride and eight of 30 normal subjects had a positive irritant patch reading at 4 days with 0.5% chlorphenesin in petrolatum. Although benzalkonium chloride was highly positive for skin reactions in our study, most reactions were probably irritation. MCI/MI and thimerosal showed highly positive allergy reactions in our study. The optimum concentration of chlorphenesin to avoid skin reactions is less than 0.5%.     

A left versus right side comparative study of Epiquick™ patch test results in 100 consecutive patients

4 strips of 5 Epiquick patch tests (19 allergens plus 1 control) were applied symmetrically in duplicate on the left and right sides of the upper back in 100 consecutive patients. 70 positive allergic patch test reactions were recorded on the left side and 67 on the right side. 67 positive reactions were concordant on both sides (64 with the same score of intensity and 3 with a different score). 3 positive reactions (in 2 patients) on the left side were negative on the right side (1 TMTD, 1 cobalt chloride and 1 wool alcohols). At rechallenge 6 weeks later, they were positive. No explanation could be found for negative results at the first challenge on one side and not on the other. The rate of non-reproducible positive results to the overall number of positive reactions was 4.2%. The good reproducibility rate (95.8%) provides useful information for further comparative studies.