Evaluation of patients patch tested with baseline series metal allergens (Ni, Co, Cr, Pd) between 1996-2021at the allergy outpatient clinic of our department of dermatology

Introduction Allergic contact dermatitis (ACD) is an important skin disease caused by contact allergens, worsening the quality of life and leading to job loss. The most common contact allergens are metals. Metal contact allergens are routinely tested in many baseline patch test series, and legal measures are being taken to reduce the incidence of metal contact sensitization in some countries. Due to the variability of sources in metal contact sensitization, it is becoming more important for each country to have its own data. In this study, we aimed to determine the frequency of metal contact sensitization in a large group of patients from Turkey, examine the changes in sensitization rates according to years, investigate the clinical relevance of contact sensitizations, and reveal the source of contact sensitizations. These results may serve as a reference for the follow-up of legal regulations regarding contact sources with metals in our country. Materials and Methods In this retrospective, cross-sectional, single-center study, we evaluated 2932 patients with suspect of ACD, who underwent patch testing with at least one metal allergen, i.e., nickel, cobalt, chromium and palladium, at the Allergy Outpatient Clinic of Istanbul Faculty of Medicine, Department of Dermatology and Venereology between June 1996 and June 2021. The files of the patients were examined in terms of demographic characteristics (age, gender, test year, presence of atopy), patch test findings (frequency, time and strength of positive reactions to metals), the clinical and occupational relevance of positive reactions, sources of contact sensitizations, follow-up period, and disease course after ACD diagnosis. Results The positivity rate to metals in the baseline patch test series was 28.4% (832/2932). 92.1% (758/832) of the cases that showed positive reactions to metal contact allergens were adults (over 18 years old), and 63.9% (532/832) were women. Metal contact allergens with the most common positive reactions were nickel 21.1% (619/2930), chromium 8.9% (258/2908), palladium 8.9% (256/2880) and cobalt 7.1% (207/2906). Metal allergens, mostly (870/1340, 64.9%) showed strong positive patch tests reactions (++/+++). Most positive reactions (95%) were early positive reactions starting within 48 and 72 hours. The most common irritant patch test reactions occurred with cobalt (380/2906, 13.1%) and the frequency of irritant reactions with baseline series metals was 6.4% (742/11624). Metal contact allergens were responsible for the current clinical situation in 39.2% (326/832) of the cases, leading to the diagnosis of ACD accordingly. Metals-related ACD occurred due to non-occupational contact sources in 52.5% (171/326) of the patients, and occupational contact sources in 47.5% (155/326). Positive patch test reactions and non-occupational ACD from metals were significantly higher in women, and occupational ACD in men. Positive patch test reactions with metal allergens as well as non-occupational and occupational ACD from metals were significantly more frequent between the ages of 18-40. Non-occupational ACD was significantly higher in the 10-17 age group and significantly lower over the age of 40. Metals-related occupational ACD was detected at a higher rate between 1996 and 2000. The highest rate of occupation was among the construction workers. Although the rate of atopy was higher in metal-related non-occupational ACD cases than the general patch test population, there was no significant correlation concerning the presence of atopy. In metals-related occupational ACD cases, the rate of atopy was significantly lower. Positive reactions with metals and metals-related non-occupational ACD were significantly higher in those with a history of metal sensitivity. There was no significant relationship between the type of application to our unit and positive patch test reactions with metals or non-occupational ACD. Non-occupational ACD was seen most frequently (100/171, 58.5%) as eczema at the contact sites of metal objects. 19.3% (33/171) of non-occupational ACD cases were evaluated as systemic allergic dermatitis (SAD), and SAD mainly presented with dyshidrosiform hand-foot eczema (11/33, 33.3%). In addition, allergic contact stomatitis was observed in 2.9% (5/171) of non-occupational ACD cases. The most common sources of metals-related non-occupational ACD were metal jewellery (62/171, 36.3%), foods (33/171, 19.3%), and metal accessories of clothes (24/171, 14%). Metals-related occupational ACD most commonly presented with hand eczema (154/155, 99.4%). While isolated hand eczema was observed in 103 of them (103/155, 66.5%), in the remaining 51 patients, it was accompanied by eczema in different localizations, most commonly the arms and forearms (n=30), feet (n=23) and face (n=19). Hand-foot eczema was significantly higher, especially in construction workers. Airborne eczema was observed in 15.5% (24/155) of occupational ACD cases. The most common contact sources of metal-related occupational ACD were cement (127/155, 81.9%), metal tools and equipments (23/155, 14.8%), metal and/or metal dust/fume (11/155, %7). Construction workers and metal workers were the most affected occupational groups. Positive patch test reactions to metals, either isolated or in different combinations, were examined in terms of independent variables. Following features were found as independent risk factors: - In isolated nickel positivity; female gender, being under 40 years old, non-occupational clinical relevance, presence of metal sensitivity, absence of hand eczema - In isolated chromium positivity; male gender, being over 40 years old, non-occupational and occupational clinical relevance, absence of metal sensitivity, being diagnosed in the early period of the study (2008 and before) - In cobalt and chromium positivity; male gender, non-occupational and occupational clinical relevance - In nickel and cobalt positivity; female gender, non-occupational clinical relevance, presence of metal sensitivity, being diagnosed in the late period of the study (2009 and after) - In the presence of all three metals positivity; male gender, non-occupational and occupational clinical relevance, presence of metal sensitivity and metal contact site eczema. In our study, the prevalence of nickel and chromium sensitization was quite high compared to many European countries. The fact that there was no decrease in the prevalence of total metal sensitization over 26 years indicates that this problem is still current. With these results, the necessity of establishing restrictive regulations regarding nickel and chromium contact sources in our country is better understood.