Contact allergy to textile dye mix in consecutively patch tested Danish eczema patients: An observational study with historical data from 2015 to 2023

Disperse dyes (DDs) are used in the dyeing of synthetic fibres in the textile industry and may cause contact allergy. In the European Baseline Series (EBS), DDs are tested as part of textile dye mix (TDM) 6.6% in pet. introduced in 2015.1, 2 TDM is composed of eight different DDs: Disperse Blue 35; Disperse Orange (DO) 1 and 3; Disperse Red 1 and 17; Disperse Yellow 3 (all 1% in pet.); Disperse Blue 106 and Blue 124 (both 0.3% in pet.).2 Supplementary textile series for patients under special suspicion of textile dye CA exist.3 Due to many concomitant reactions between PPD and DO 3 and TDM respectively, it has been discussed whether DO 3 should be excluded from TDM.4-7 More knowledge on long-term trends of contact allergy to DDs is warranted. A retrospective observational study with historical data from Gentofte Hospital, Denmark, was conducted. Consecutively patients ≥18 years old patch tested with TDM 6.6% in pet. from 2015 to 20231 were included. Patch testing and reading of reactions were performed as previously described.8 Patients patch tested more than once during our study period were handled as previously.8 Information on the MOAHLFA-index (male, occupational dermatitis, atopic dermatitis AD, hand eczema, leg eczema, facial eczema, age >40) and current clinical relevance were extracted. Cochran–Armitage test for trend was used to assess trends across test years. Associations between CA to TDM and the factors of the MOAHLFA-index were assessed using logistic regression models adjusting for age >40/≤40, sex, and AD. As sub-analysis, data on patients patch tested with at least one of the single components of TDM (all 1% in pet.) and/or PPD (1% in pet.) were extracted. Only patients with suspected contact allergy to DDs are tested with both TDM and the single components of TDM at our centre. However, some patients may have been tested with DDs without being co-tested with TDM for unknown reasons due to the use of historical clinical data. An alpha level of 0.05 was used to apply for significance. 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). A total of 5495 unique patients were patch tested with TDM in the period from 2015 to 2023. The overall prevalence of CA to TDM was 2.3% (128/5495) with no significant trend across the period (Cochran–Armitage, p = 0.93) (Figure 1). The current clinical relevance for patients with CA to TDM was 31.5% (39/124). CA to TDM was significantly positively associated with leg eczema (Table 1). The prevalence of CA to the single DDs of TDM and concomitant reactions between TDM and its individual DDs are presented in Tables S1–S3. The most prevalent DD of TDM causing CA is DO 3 (6.2%, 8/129). Concomitant reactions between PPD and DO 3 showed that of patients reacting to DO 3, 85.7% (6/7) also reacted to PPD and of patients reacting to PPD, 66.7% (6/9) also reacted to DO 3. Four of the six patients who reacted to both PPD and DO 3 had a 2+ reaction to both allergens. Likewise, of patients reacting to PPD, 48.9% (67/137) also reacted to TDM and of patients reacting to TDM, 57.8% (67/116) also reacted to PPD. This study provides important insight into the epidemiology of CA to TDM from 2015 to 2023. The prevalence of CA to TDM was high (2.3%) but lower than reported by the European Surveillance System on Contact Allergies 2019/2020 data (3.6%).9 The stable and high frequency of CA to TDM underscores the importance of the test in the EBS. Furthermore, TDM proved a good marker for CA to its individual DDs. The most frequent DD causing CA in TDM allergic patients is DO 3, as previously reported.3 Our data show that almost all patients reacting to DO 3 also reacted to PPD, which supports the exclusion of DO 3 from TDM.7 Instead, TDM II 7% in pet. (DO 3 excluded, all other DDs of TDM 1% in pet.) could be introduced as also previously suggested by Isaksson et al.7 However, considering our small sample size of DO 3 positive patients, it would be of interest to temporarily include DO 3 in supplementary standard series for better surveillance. Christoffer Kursawe Larsen: Conceptualization; methodology; formal analysis; writing – original draft; writing – review and editing; project administration. Mikkel Bak Jensen: Conceptualization; methodology; writing – review and editing; project administration. Jakob F. B. Schwensen: Supervision; writing – review and editing. 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. Table S1. The prevalence of patients with contact allergy to a single component of textile dye mix among all patients patch tested with the single component in the period from 2015 to 2023. Table S2. Patients with positive reaction to a specific component of textile dye mix (TDM) among all patients co-tested with and having positive reaction to TDM. Table S3. Patients with positive reaction to textile dye mix (TDM) among all patients co-tested with and reacting to the specific component of TDM. 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.