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Evolving role of the atopy patch test in the diagnosis of food allergy.

The atopy patch test has developed into a valuable additional tool in the diagnostic work-up of food allergy in infants and children with atopic dermatitis. A positive atopy patch test may help to prevent imposing restrictive and unnecessary diets after misjudging late reactions by clinical assessment alone. Furthermore, the combination of positive atopy patch tests together with defined levels of specific IgE makes double-blind, placebo-controlled food challenges superfluous in some cases. However, several open questions indicate the need for further studies.

Child Welfare↗

Sensitivity, specificity and positive predictive value of patch testing: the more you test, the more you get? ESCD Working Party on Epidemiology.

Pathophysiological variability affects the results of patch testing. In addition, even a minimal degree of test-imprecision due to this variability has a number of important statistical consequences for the analysis and interpretation of any patch test data set. One such statistical phenomenon that is often overlooked is the dependence of the positive predictive value (i.e., the predictive value of a positive patch test) on sensitivity and specificity, the impact of which is heavily dependent on the proportion of truly allergic subjects that are studied. A 2nd important issue is the fact that patch testing is performed in series, which means multiple tests. If we assume, for example, a patch test series of only 10 allergens, then it can be demonstrated that there is a random probability of over 40%) to find, simply by chance, for at least 1 allergen, a statistically significant difference between 2 groups of patients. Comparison of the results of series between patients calls for statistical adjustments in order to prevent erroneously positive differences and/or associations.

Dermatitis, Allergic Contact↗

Managing the excited skin syndrome: patch testing hyperirritable skin.

Inflammation-modulating phenomena (IMPs), humoral and cellular, fluctuate during the course of irritant and allergic contact dermatitis influencing irritability of the skin. The patch test procedure is a biological assay, a titration of responses of IMPs which can produce hyporeactivity or hyperirritability of the skin of patients who have dermatitis (PDs) and a single patch test is a 'snapshot' of the tempo of an evolving process. The excited skin syndrome (ESS) refers to hyperirritability from clinical and patch test dermatitis creating false-positive patch test reactions which are not reproducible when dermatitis and IMPs have subsided. During ESS, the threshold for irritancy decreases and irritant reactions increase. Patch test concentrations should be determined and ESS investigated in PDs having enhanced IMPs, not in 'normal' individuals, and if a patch test result is important to a patient the test should be performed more than once. Variable reproducibility is inherent in the patch test method, but ESS can be managed by appropriate testing and retesting, and search for relevance.

Adult↗

The role of vehicles in diagnostic patch testing. A reappraisal.

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.

Allergens↗

The utility of patch tests using larger screening series of allergens.

BACKGROUND: The number of patch test allergens available within the United States for routine commercial purchase is limited. Allergens chosen for inclusion in routine screening series or patch test trays vary, and the degree of information obtained from any series may or may not serve a patient's needs. OBJECTIVE: Knowledge of how well the allergens chosen for inclusion in the two commercially available sources perform compared with a more expansive panel of tests can help physicians select the more appropriate tests. METHODS: From 1994 to mid-1997, 554 patients were tested with allergens recommended by the North American Contact Dermatitis Group (NACDG). This included all allergens currently available from both current domestic sources, although not in the identical form used by the Thin-layer Rapid Use Epicutaneous Test (TRUE) test (Glaxo Dermatology, Research Triangle Park, NC). Another 185 patients were tested with supplemental series of allergens. RESULTS: The larger the series of allergens used, the more positive tests were found and the more relevant tests as well. Hermal patch test allergens identified about 55% of the information found by the NACDG series; the TRUE test allergens (but not in the TRUE test system) identified 65%. Of the 103 reactions to supplemental allergens not found by the NACDG series, 59 were relevant. CONCLUSION: Larger series of allergens can enhance accurate diagnosis of allergic contact dermatitis. No single arbitrary series of allergens can adequately survey the contemporary environment of individual patients. Selection of allergens for testing requires consideration of the patient's history and access to appropriate environmental contactants.

Acrolein↗

Retrospective survey of patch testing at department of dermatology and venerology, zagreb university hospital center in zagreb, croatia.

Epicutaneous (patch) test is a standard test to confirm contact allergy. During a six-year period (1998-2003), contact allergic dermatitis was diagnosed in 4132 (65%) of 6341 patients using standard patch test with a Croatian series of allergens according to the International Contact Dermatitis Research Group (ICDRG). The most common clinical diagnoses related to contact allergy (male; female) were contact allergic dermatitis (65.4%; 72.2%); atopic dermatitis (15.9%; 11.7%); contact irritant dermatitis (7.0%; 6.6%) and nummular eczematoid dermatitis (4.2%; 2.4%). According to occupation, positive patch test reaction was most commonly observed in workers, whereas 65% of patients showed positive reactions to one or more substances. There was an increased frequency of positive patch test reactions to potassium dichromate, nickel sulfate, thimerosal and neomycine sulfate, along with a significant decrease in the frequency of positive patch test reactions to cobalt chloride, carba mix, wood tars, detergents, parabens mixture, urushiol and rubber mixture. We strongly recommend keeping up-to-date with the epidemiology of contact allergy in Croatia.

Adult↗

Individual and instrumental variations in irritant patch-test reactions--clinical evaluation and quantification by bioengineering methods.

A major purpose of irritant patch testing is to differentiate between normal, delicate and less sensitive skin. To assess the usefulness of irritant patch testing, knowledge of variation in responses to identical patch tests is essential. In the present study inter- and intra-individual variation in irritant patch test reactions due to sodium lauryl sulphate and nonanoic acid is given when evaluated by traditional visual scoring as well as different non-invasive methods, i.e. measurement of transepidermal water loss, the hydration state of stratum corneum by electrical conductance, cutaneous blood flow by laser Doppler flowmetry, and measurement of skin thickness by 20-MHz ultrasound A-scan. The intra-individual 'site-to-site' variation was considerably less than the inter-individual variation, which is essential to differentiate between persons with delicate and less sensitive skin. Methods used were relevant for this purpose except for the measurement of electrical conductance.

Adult↗

Contact allergy to ophthalmic dipivalyl epinephrine hydrochloride: demonstration by patch testing.

A patient presented with a 3-month history of conjunctivitis and periocular eczema. He had a 3-year history of glaucoma and was being treated with 3 different locally applied eyedrops (Timoptic (timolol maleate) ophthalmic solution 0.25%, Pilocar (pilocarpine) ophthalmic solution 1%, and Propine (dipivalyl epinephrine hydrochloride) ophthalmic solution 0.1%). Patch testing with all 3 undiluted eyedrop solutions revealed a reaction only to Propine eyedrops. Patch testing to the individual components of Propine eyedrops revealed an allergic reaction to 0.5% dipivalyl epinephrine hydrochloride that was apparent on the 2nd patch test reading. After discontinuing the Propine eyedrops, the conjunctivitis as well as the periocular dermatitis resolved, proving that the positive patch tests were relevant to both. It was reported that re-exposure to dipivalyl epinephrine hydrochloride by intra-ocular challenge was necessary to diagnose this allergy. This is the first demonstration of dipivalyl epinephrine hydrochloride allergy by patch testing. Since the 1st patch test reading (2 days) was weak, 2nd patch test (4 days) readings may be important in diagnosing this allergy by patch testing.

Aged↗

Reproducibility of atopy patch tests with Dermatophagoides: a study on 85 patients with atopic dermatitis.

Atopy patch tests (APTs) are considered a useful addition to standard testing procedures for the identification of allergens triggering the appearance of eczema in patients with atopic dermatitis (AD). The aim of the study was to evaluate the reproducibility of APTs with house dust mites by simultaneously patch testing AD patients. 85 subjects affected by AD, 36 males and 48 females, aged from 1 to 52 years, were patch tested with Dermatophagoides mix (D. pteron/D. farinae) 20% pet. In our patients, the percentage of agreement between the frequency of positive and negative responses to Dermatophagoides mix was 96.7%. Reproducibility was highly satisfactory, as evaluated by k-value (0.953). As regards the agreement in the intensity of APT responses to Dermatophagoides mix between the right and left sides, we found that reproducibility was also highly satisfactory (k = 0.851). In conclusion, for Dermatophagoides APTs, the agreement rate was similar to that of standard patch tests, and therefore APTs may be considered sufficiently reproducible to be employed as a diagnostic testing procedure.

Adolescent↗

The quantification of patch test responses: a comparison between echographic and colorimetric methods.

Patch testing is widely used both for clinical and experimental purposes. Although the clinical grading employed routinely is of practical value, the lack of objectivity makes it unsuitable for research purposes and dose-response analysis studies. Instrumental measuring techniques have been applied to patch test evaluation, because they enable objective quantification of different biophysical aspects of the inflammatory reaction by means of a continuous assessment scale, providing data suitable for statistical analysis. In order to compare the colorimetric and echographic methods for the evaluation of reactions of different intensity, we performed patch tests with 5% nickel sulfate on the flexor aspect of the forearm in 120 nickel-sensitive patients. Clinical and instrumental measurements were performed at 72 h. Numerical values corresponding to instrumental measurements were compared to the positivity degree, as assessed clinically. Whereas echographic parameters, expressing the intensity of oedema and inflammatory infiltration, enabled a distinction between +, +2 and +3 reactions, colorimetric a* values, describing erythema, failed to distinguish between +2 and +3 reactions. Thus, the use of ultrasound is advisable for the quantification of skin reactions of great intensity, whereas the colorimetric method could be usefully employed for dose-response studies assessing minimal eliciting concentrations of allergens, and for the evaluation of clinically undetectable reactions.

Adult↗

Is the test patch useful in determining safety against operative infection?

The practice of pre-operative 'Test Patch' on any eye continues to be an important, conventional step at a number of eye infirmaries. The present study was carried out on eighty seven eyes to determine the relevance of Test Patch as a prelude to surgery. After a critical analysis of the result of investigation, it is concluded that the 'Test Patch' does not provide a statistically reliable information regarding potential bacterial infection since there is no correlation between pre-patching and post-patching clinical appearance, and bacterial isolates in a given case. Presence of polymorphs or organisms in the Grams stained conjunctival smears did not make any difference with regard to a positive or negative bacterial growth in a given eye. It is concluded that 'Test Patch' neither predicts nor helps in any way in a case waiting to undergo intra ocular surgery. The Test Patch, therefore, at best, can serve as an acclimatizing exercise that simulates bandaging in the post-operative period.

Bacterial Infections↗

The aluminum content in some patch test allergens.

The Al content of 18 patch test allergens were measured by electrothermal atomic absorption spectrophotometry. It was found that these preparations contained Al in various amounts. We conclude that the presence of Al in patch test allergens may interfere with the diagnosis and evaluations of patients to whom the test is applied.

Allergens↗

A clinically relevant contact allergy to methyldibromo glutaronitrile at 1% (0.32 mg/cm) detected by a patch test.

Recently, the preservative methyldibromo glutaronitrile (MDBGN) at 0.5% w/w in petrolatum was included in the European standard patch test series based on the studies on chemical stability and consideration of rates of contact allergy, doubtful and irritant reactions as well as information on clinical relevance represented by results of a repeated open application test (ROAT) and patch test concentrations required to diagnose allergic contact dermatitis from MDBGN in individual cases. In this report, a case with a clinically relevant contact allergy to MDBGN, which on the mandatory reading occasion on D3 only was traced by a patch test with MDBGN at 1.0% (0.32 mg/cm2), is presented. The patient suffered from a chronic hand dermatitis, and when the patient stopped using a liquid soap containing MDBGN, the hand dermatitis substantially improved. A ROAT performed in a blinded and controlled way with applications twice daily on the hands with 2 moisturizers with and without MDBGN resulted in a deterioration of the hand dermatitis on the hand to which the MDBGN-preserved moisturizer had been applied.

Allergens↗

Patch testing over tattoos.

BACKGROUND: There is little, if any, literature regarding placing and reading of patch-tests on tattooed skin. METHOD: A patient whose entire back was covered with multiple tattoos was patch-tested. RESULTS: Multiple positive patch-tests were seen with no apparent reduction in intensity related to tattooed skin. CONCLUSION: If necessary, patch-tests can be placed and read on tattooed skin.

Adult↗

Study of persistence and loss of patch test reactions to dichromate and cobalt.

Hyposensitization is a poorly understood phenomenon that refers to the conversion from a positive to a negative (or less positive) patch test. We studied 180 cement workers with contact dermatitis, who originally had a total of 163 positive patch test reactions to potassium dichromate and 98 positive reactions to cobalt chloride. They were patch tested a 2nd time after 2-6 years. On the 2nd patch test to dichromate, 103 (63%) remained positive, while reactivity decreased in 33 (20%) and 27 (17%) had become non-reactive. Cobalt sensitivity persisted in 47%, diminished in 13%, and 40% of the patch tests became non-reactive. In 10 patients with persistent patch test reactions and 10 matched patients with diminished reactions or loss of reactivity, circulating T-cell responses to dichromate and cobalt were studied in vivo. Circulating T cells that proliferated only to specific contact allergens were isolated and in all patients they were primarily CD4+. However, in patients with persistent reactions, they were CD4+ CD45RA+ (suppressor - inducer cells). These differences support an immunologic basis for hyposensitization.

Adult↗

The incidence of allergy to propolis in 605 consecutive patients patch tested in Prague.

605 consecutive patients were patch tested with the standard CDRG test series and with a 10% alcoholic solution of propolis. Positive allergic reactions to propolis were observed in 25 patients (4.2%); thirteen of them exhibited a simultaneous positive patch test to balsam of Peru. In view of the relatively high incidence of allergic reactions and the appearance of pseudo-cross-sensitivity to another common allergen, balsam of Peru, propolis should not be used in topical medicaments or as a component of cosmetic preparations.

Administration, Cutaneous↗

Patch-test reactions to plastic and glue allergens.

Plastics and glues are common causes of occupational dermatoses, but only few reports have dealt with patch-test reactions caused by plastic and glue allergens. Patients exposed to plastics and remitted to an occupational dermatology clinic, were patch-tested with 50-53 plastic and glue allergens during a 6-year period. Conventional patch-test techniques were used. The most common causes of allergic patch-test reactions in 360 patients were novolac epoxy resin (5.1%), phenol formaldehyde resin (3.1%), 4-tert-butylcatechol (2.6%), phenyl glycidyl ether (2.6%), diaminodiphenyl methane (2.2%), benzoyl peroxide (2.2%), hexamethylene tetramine (2.0%) and o-cresyl glycidyl ether (1.6%). The allergens that most often elicited irritant patch-test reactions were: benzoyl peroxide (9.5%), abitol alcohol (3.6%), hydroquinone (3.1%), acid-catalyzed phenol formaldehyde resin (2.5%) and toluene diisocyanate (1.9%). Twenty-six out of 53 chemicals caused no allergic reaction during the 6-year period. Plastic allergens in the standard series provoked allergic reactions with formaldehyde (5.8%), diglycidyl ether of bisphenol A (3.2%), 4-tert-butylphenol-formaldehyde-resin (1.1%), toluene sulphonamide formaldehyde-resin (1.1%) and triethylenglycol diacrylate (0.4%). Although half of the plastic chemicals gave no allergic patch-test reactions during a 6-year period, with unusual allergens this low yield needs to be accepted, because otherwise rare allergies will not be detected. Also a negative reaction has diagnostic value.

Acrylic Resins↗

Dynamic patterns of allergic patch test reactions to 10 European standard allergens. An analysis of data recorded by the Information Network of Departments of Dermatology (IVDK).

Insight into the dynamic time courses of patch test reactions may be useful for patch test evaluation. To put this to the proof, we have analysed the time courses of allergic patch test reactions that were filed between 1990 and 1994 by the Information Network of Departments of Dermatology in Germany (IVDK). Based on reaction strength at days 1 to 3, each allergic patch test was assigned to 1 of 5 distinct dynamic reaction patterns: crescendo, plateau, decrescendo, crescendo/decrescendo, or decrescendo/ crescendo. The frequencies of these patterns were determined for those 10 standard allergens yielding the highest numbers of allergic reactions (n between 180 and 1240), and dynamic patterns were classified as type 1 (crescendo or plateau patterns) or type 2 (other patterns). Influences of population characteristics upon the classification of patterns were evaluated by logistic regression analyses. Different frequencies of reaction patterns were found for distinct allergens. For all 10 allergens, type-1 patterns were significantly more often observed for allergic reactions assessed as clinically relevant. For 5 allergens, female sex of patients was associated with a lower frequency of type-2 patterns. A history of atopic dermatitis and the age of patients were only weakly associated with a certain classification of reaction patterns in some of the allergens. In a comparison of reaction patterns obtained with different allergens in the same population, we found that nickel sulfate elicited type 1 reaction patterns more often than fragrance mix. We conclude that the dynamic reaction patterns should be taken into account in the evaluation of patch tests. The relation of type-1 patterns to clinical relevance of the reaction needs further attention.

Adult↗