Shoe Allergens: A Retrospective Analysis of Cross-sectional Data From the North American Contact Dermatitis Group, 2005–2018

Abstract

Background: Shoe contact allergy can be difficult to diagnose and manage. Objective: The aim of the study was to characterize demographics, clinical characteristics, patch test results, and occupational data for the North American Contact Dermatitis Group patients with shoe contact allergy.Methods: This is a retrospective study of 33,661 patients, patch tested from 2005 to 2018, with a shoe source, foot as 1 of 3 sites of dermatitis, and final primary diagnosis of allergic contact dermatitis.Results: Three hundred fifty-two patients met the inclusion criteria. They were more likely to be male (odds ratio = 3.36, confidence interval = 2.71-4.17) and less likely to be older than 40 years (odds ratio = 0.49, confidence interval = 0.40-0.61) compared with others with positive patch test reactions. The most common relevant North American Contact Dermatitis Group screening allergens were potassium dichromate (29.8%), p-tert-butylphenol formaldehyde resin (20.1%), thiuram mix (13.3%), mixed dialkyl thioureas (12.6%), and carba mix (12%). A total of 29.8% (105/352) had positive patch test reactions to supplemental allergens, and 12.2% (43/352) only had reactions to supplemental allergens. Conclusions: Shoe contact allergy was more common in younger and male patients. Potassium dichromate and p-tert-butylphenol formaldehyde resin were the top shoe allergens. Testing supplemental allergens, personal care products, and shoe components should be part of a comprehensive evaluation of suspected shoe contact allergy.C ontact allergy to shoes is a common yet difficult problem of varying prevalence. 1 Shoes are created from diverse components, including rubber, adhesives, leather, tanning agents, dyes, metals, and/ or textiles. Sensitization can develop to 1 or more of these components; the most common affected area is the dorsal feet. 1,2 Patch testing is the criterion standard for establishing type IV hypersensitivity; comprehensive patch testing with screening and supplemental allergens, as well as personal care products and shoe components, is important in the setting of suspected shoe contact allergy. 3,4 Understanding the epidemiology of shoe allergens and allergen avoidance in patients with

Allergic contact dermatitis to footwear in Thailand: Prevalence, clinical characteristics and common allergens

“…Notably, India reported a substantially higher prevalence, ranging from 13.4% to 24.2% (Table 3). 2,3,[9][10][11][12][13][14][15][16][17][18][19][20][21][22] Our data demonstrated a higher likelihood of females developing footwear ACD than males. This finding aligns with the majority of previous studies (Table 3).…”

“…Furthermore, studies conducted in North America have reported a slight predominance of males exhibiting footwear ACD. 2,21 The reality is that footwear ACD can occur in either sex, depending on lifestyle choices, footwear materials and types of footwear.…”

“…Footwear ACD can cause significant discomfort and impairment of quality of life 1 . The reported prevalence of footwear ACD ranges from 0.2% to 24.2% in contact dermatitis clinics worldwide 2,3 …”

Importance of Supplemental Patch Testing Beyond a Screening Series for Patients With Dermatitis

“…Specific allergens reported in footwear dermatitis are variable depending on fashion styles, manufacturing processes, climate, and geographic conditions . A previous analysis of NACDG data revealed that 29.8% of patients with shoe contact allergy had positive patch test reactions to supplemental allergens and the screening series did not identify the specific shoe allergen in 12.2% of the cases . Similar to clothing, patch testing for suspected shoe allergy often involves patch testing with samples of patients’ own footwear.…”

“…44 A previous analysis of NACDG data revealed that 29.8% of patients with shoe contact allergy had positive patch test reactions to supplemental allergens and the screening series did not identify the specific shoe allergen in 12.2% of the cases. 45 Similar to clothing, patch testing for suspected shoe allergy often involves patch testing with samples of patients' own footwear. To avoid falsenegative results, it is important to use large pieces of shoes and clothing, moisten with water, and reapply if the result is negative at 48 hours.…”