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Contact allergy to N ‐isopropyl‐ N ′‐phenyl paraphenylenediamine in consecutively patch tested Danish eczema patients: An observational study with historical data from 2013 to 2023

2024; Wiley; Volume: 91; Issue: 4 Linguagem: Inglês

10.1111/cod.14629

1600-0536

Christoffer Kursawe Larsen, Mikkel Bak Jensen, Jakob F. Schwensen,

Occupational exposure and asthma

N-isopropyl-N′-phenyl-paraphenylenediamine (IPPD) is used as antioxidant in industrial black rubber items such as tyres and domestic rubber products such as sport watches1, 2 IPPD may cause allergic contact dermatitis known as "Volkswagen dermatitis."3 The European baseline series (EBS) contains IPPD (0.1% in pet.).4 The prevalence of contact allergy (CA) to IPPD is low in many studies ( 40), and occupation was extracted.8 Time trends were assessed using the Cochrane-Armitage test for trend. Associations between IPPD CA and the MOAHLFA-index were assessed by binary logistic regressions adjusting for sex, age >40/≤40, and atopic dermatitis. Further, crude odds ratios were calculated. As sub-analysis, patch test results on patients tested with CPPD, DPPD or N,N-di-2-naphthyl-4-phenylenediamine (all 1% in pet.) as part of the specialised rubber series from 2013 to 2023 were extracted. A p-value <0.05 was considered significant. SPSS Statistics-25 and R-version-2023.12.0 were used for statistical analysis. The study is approved under the umbrella project (p-2023-14 475), Region Hovedstaden - Forskningsjuras internal directory of active research projects. A total of 7575 unique patients were consecutively patch tested with IPPD from 2013 to 2023. The overall prevalence of CA to IPPD was 0.41% (31/7575) and a significantly decreasing trend was identified from 2013 to 2023 (Cochrane-Armitage p < 0.05) (Figure 1). The current clinical relevance was 20% (6/30). No significant associations were found between IPPD CA and any variable from the MOAHLFA-index (Table 1). The occupations among those with IPPD CA and occupational dermatitis were: Worker in food industry (n = 2); cleaner (n = 1), healthcare worker (n = 1); lab work (n = 1); warehouse work (n = 1); unemployed (n = 1). Of patients tested with CPPD, DPPD, or N,N-di-2-naphthyl-4-phenylenediamine, 0.76% (15/1975) had positive reaction to CPPD, 0.40% (8/1978) to DPPD, and 0% (0/1978) to N,N-di-2-naphthyl-4-phenylenediamine. Co-testing with IPPD and DPPD or CPPD showed that of patients reacting to IPPD, 92.3% (12/13) and 46.2% (6/13) also reacted to CPPD or DPPD, respectively. Further, all patients reacting to CPPD or DPPD also reacted to IPPD (Tables S1 and S2). In this study, we investigated the epidemiology of CA to IPPD from 2013 to 2023. The found prevalence (0.41%) is lower than reported from European Surveillance System on Contact Allergy 2019/2020 data (0.79%).9 No associations with the MOAHLFA-index were identified even though IPPD CA previously has been associated with occupational dermatitis.10 IPPD proved to be a well-screening allergen for the components of black rubber mix. The importance of IPPD in the EBS may nevertheless be questioned considering the low prevalence of IPPD CA, the decreasing trend, low clinical relevance, and lack of relevant occupations. Data used in this study are from a specialised tertiary hospital and only severe cases are included. In Demark, IPPD CA may therefore be caught elsewhere, for example, private dermatologists and departments of occupational medicine. Further surveillance data should evaluate the relevance of IPPD in the EBS. Christoffer Kursawe Larsen: Conceptualization; methodology; formal analysis; investigation; writing – original draft. Mikkel Bak Jensen: Conceptualization; investigation; methodology; formal analysis; writing – review and editing. Jakob F. B. Schwensen: Writing – review and editing; supervision. This work is supported by the Danish Environmental Protection Agency under the Ministry of Environment of Denmark. The authors declare no conflicts of interest. The data that support the findings of this study are not available upon request due to Danish data protection legislation. Supplementary Table S1. Patients with positive reaction to a specific rubber chemical from the specialised rubber series among patients reacting to IPPD. Patients tested with both the specific rubber chemical and N-isopropyl-N′-phenyl paraphenylenediamine (IPPD) are included. Supplementary Table S2. Patients reacting to IPPD among patients with positive reaction to a specific rubber chemical from the specialised rubber series. Patients tested with both the specific rubber chemical and N-isopropyl-N′-phenyl paraphenylenediamine (IPPD) are included. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.