Efficiency in patch testing: the number needed to test to get one relevant result as a new approach in the evaluation of baseline series

García‐Gavín, J.; Mercader, Patricia; Descalzo, Miguel Ángel; García‐Doval, I.; Silvestre, Juan Francisco; Sánchez‐Pérez, Javier; Fernández‐Redondo, Virginia; Armario‐Hita, J.C.; Ruíz‐González, Inmaculada; Giménez‐Arnau, Ana M.

doi:10.1111/bjd.18975

Cited by 11 publications

(8 citation statements)

References 5 publications

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“…Those that yielded the lowest added values included European corticosteroids and textile trays, with added values of 2.2% and 2.3%, respectively. Therefore, the lowest NNT, 6 which was the most effective, was obtained from the acrylate and fragrance trays, whereas the highest NNT was observed in the corticosteroid and textile trays (Table 2), implying a relatively low sensitization rate to allergens among those trays.…”

Section: Resultsmentioning

confidence: 96%

The Added Value of Patch Testing Beyond the Baseline Tray

et al. 2022

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Background: The patch test is the standard for diagnosing allergic contact dermatitis. Standardized trays allow the examination of the most prevalent allergens, whereas customized trays are more appropriate for addressing specific allergens and require expertise. They are therefore usually performed in specialized clinics.Methods: We assessed the results of 4355 patch tests performed between 2012 and 2020 in a contact dermatitis clinic located in a large tertiary medical center. All patients were tested using the European baseline series and additional trays as clinically indicated. We assessed the frequency of relevant positive reactions outside the European baseline series. We then examined the added value and number of tests (NNTs) that need to be performed to elicit one relevant positive reaction per tray and common allergens.Results: Nine hundred fifty-four patients (21.9%) had 1 or more positive relevant reactions; 43.3% tested positive for an allergen outside the European baseline series (OEBS). The acrylate and fragrance trays were highly represented among the positive and relevant reactions OEBS with NNTs of 4.4 and 6.8, respectively. 2-Hydroxyethyl methacrylate is the most prevalent allergen OEBS and is considered a marker for acrylate sensitivity with a high rate of cross-reactions and concordance rate of 85%, justifying its addition to the EBS in 2018. Other highly represented allergens include chloramphenicol, 2-hydroxyethyl acrylate, and Amerchol L-101, a lanolin derivative. The cosmetics and textile trays, although often tested, have relatively low added values of 3.7% and 2.3%, respectively. Surprisingly, the cutaneous adverse drug reaction series tray (CAD-1000) yielded no positive reactions, whereas testing the patients' medication yielded positive results in 10.9% of the cases.Conclusions: Expanded patch testing is crucial to accurately diagnose allergic contact dermatitis and almost doubles the number of patients with relevant positive reactions. Acrylate sensitivity is an emerging epidemic with a high positive reaction rate and low NNT, as is sensitivity to the allergens in the fragrance tray. 2-Hydroxyethyl methacrylate is a reliable marker for acrylate sensitivity with a concordance rate of 85%. Chloramphenicol is a common culprit and should be added to the standard tray in countries with a high usage rate. A low NNT was also observed when testing the patients' own cosmetics and medications; this should, therefore, be encouraged. The textile tray yielded a relatively high NNT; however, it should be performed when clinically indicated in the absence of a reliable marker in the EBS.

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Section: Resultsmentioning

confidence: 96%

The Added Value of Patch Testing Beyond the Baseline Tray

et al. 2022

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“…Although there are reports in Europe about the use of MDBGN in topical drugs 17 or a detergent for leather, 18 these cases must be considered the exception, rather than the rule, since a widespread non‐compliance with the law seems unlikely. In terms of efficiency, our data show that when we patch test MDBGN as a component of the baseline series, it is necessary to perform 5072 tests to obtain one positive relevant result 12 . Probably, most cases of contact allergy to MDBGN in our series represent historical sensitizations that developed years ago, when the use of this preservative was still widespread.…”

Section: Discussionmentioning

confidence: 92%

“…We observed a similar frequency of sensitization, but, unlike the previous study, current relevance could be ascertained in only one patient (1/114, 0.87%). Another Spanish study 12 that analyzed data from 2004 to 2014 in eight centres, found contact allergy to MDBGN in 121 out of 8217 patients (1.47%), with only four being of current relevance (4/121, 3.3%).…”

Section: Discussionmentioning

confidence: 99%

“…These policies led to a significant decrease in the prevalence of contact allergy to MDBGN 9,10 . Accordingly, it was difficult to evaluate the relevance of most positive patch tests from then on 11,12 . Some authors advocated maintaining MDBGN in the baseline series, based on possible non‐regulated sources that could explain new cases of sensitization and dermatitis elicitation among young people 13 .…”

Section: Introductionmentioning

confidence: 99%

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Should methyldibromo glutaronitrile continue to be used in the European baseline Series? A REIDAC national cross‐sectional study

et al. 2021

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Background Methyldibromo glutaronitrile (MDBGN) was one of the most frequent and relevant allergens found in patch testing at the beginning of this century. In 2008, this preservative was banned from cosmetics in Europe and ever since the prevalence of contact allergy to MDBGN has progressively decreased. Despite that gradual decline, MDBGN is still patch‐tested in most baseline series. This study assessed the frequency of MDBGN sensitization, epidemiological characteristics of allergic patients, and the relevance of positive patch tests in a nationwide Spanish registry (REIDAC). Patients and methods We evaluated consecutively patch‐tested patients in all participating centres. Using these data, we calculated the proportion of patients with positive patch tests to MDBGN from June 2018 to June 2020 and evaluated the relevance of the positive patch tests. Results One hundred and fourteen out of 5072 (2.24 %) tested patients were sensitized to MDBGN. Clinical current relevance was confirmed in only one case. Conclusion Although the frequency of contact allergy to MDBGN remains high, no clinical significance was found in most of these patients (5072 tests needed to obtain one relevant positive result). The clinical usefulness of this allergen seems weak and its continued inclusion in the European baseline series is questionable.

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“…Some authors, when unable to confirm current relevance based on label information, have suggested that most reactions are irritant, doubtful, false-positive, or of only past relevance. 1,[3][4][5][6][7] Some authors have even recently suggested that MDBGN/ DBDCB be deleted from the European baseline series, 1,3,4 and it has been decided by the American Contact Dermatitis Society to that the substance be removed from its core allergen series, 6 despite relatively high prevalence of contact allergy. 1,[8][9][10] We consider that omitting the substance from the baseline series, instead of tracking exposure more efficiently, will harm surveillance and prevention of skin sensitization and allergic contact dermatitis.…”

Section: Patch Testing With Mdbgn/dbdcbmentioning

confidence: 99%