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

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.

Are the Spanish baseline series markers sufficient to detect contact allergy to corticosteroids in Spain? A GEIDAC prospective study.

BACKGROUND: Corticosteroids are among the most commonly used topical drugs. Contact allergy to these exists, but can be easily missed. Corticosteroid screening markers have been included in the baseline series with the aim of detecting most of the sensitized patients. OBJECTIVES: To assess the prevalence of contact allergy to topical corticosteroids in Spain and examine the usefulness of corticosteroid markers to detect contact allergy to corticosteroids. METHODS: In total, 3699 patients referred to 20 dermatology departments across Spain for patch testing with the baseline series, including budesonide and tixocortol pivalate, were also tested with six supplementary corticosteroids (methylprednisolone aceponate, mometasone furoate, prednicarbate, clobetasol propionate, betamethasone 17-valerate, and betamethasone 17,21-dipropionate). Additionally, 2547 (68.8%) patients were tested with hydrocortisone 17-butyrate. RESULTS: Fifty-four patients showed positive reactions to at least one of all tested corticosteroids (1.46%). Thirty-nine (1.05%) reacted to at least one of the additionally tested corticosteroids; among these, 24 of 39 (61.5%) did not react to any of the corticosteroid allergy screening markers tested. CONCLUSIONS: More than half of the patients who were allergic to the additionally tested corticosteroids were not detected with the corticosteroid allergy markers. An update of the corticosteroid allergy screening markers is encouraged, with consideration of group 3 corticosteroids.