Clinical Dermatology Review

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 4  |  Issue : 2  |  Page : 149--154

A study on the role of footwear as a cause of foot eczema using patch test


Neema Sandra Dias, B Nanda Kishore, D Sukumar 
 Department of Dermatology, Father Muller Medical College, Mangalore, Karnataka, India

Correspondence Address:
B Nanda Kishore
Department of Dermatology, Father Muller Medical College, Mangalore - 575 002, Karnataka
India

Abstract

Background: Foot eczema is an allergic contact dermatitis which runs a chronic course due to the ignorance of the causative agent. Patch test is a safe and simple outpatient diagnostic procedure for all kinds of allergic contact dermatitis. Aims and Objectives: This study was done to find the role of footwear as a cause of foot eczema and to know the most common allergen in the footwear causing foot eczema by Patch testing. Materials and Methods: A total of 71 patients were enrolled in the study who presented with foot eczema. Meticulous history was taken and clinical examination was done on all patients. A patch test using Indian footwear series containing 15 allergens was performed, and results were recorded after 48 h. Results: In our study comprising 71 patients, age of the patients ranged from 13 to 70 years with a slight female preponderance. Plantar surface of foot was the most common site involved (35.2%) with a winter aggravation (21.1%). A total of 63.4% of patients were tested positive for one or more allergens present in the footwear. Footwear was reported to be an inciting agent in 36.4% patients, and 82.6% of these were tested positive. Black rubber mix (22.53%), nickel (14.08%), and colophony (12.67%) were the most common sensitizers. Conclusion: A significant incidence of footwear as a causation of foot eczema was concluded, with rubber and metals being the most common allergens. It is noteworthy to consider employing patch test routinely to know the causation of footwear in the foot eczema so that appropriate footwear can be used. However, it would be helpful if we could detect the specific allergen in a footwear to help these patients suffering a relapsing chronic dermatitis.



How to cite this article:
Dias NS, Kishore B N, Sukumar D. A study on the role of footwear as a cause of foot eczema using patch test.Clin Dermatol Rev 2020;4:149-154


How to cite this URL:
Dias NS, Kishore B N, Sukumar D. A study on the role of footwear as a cause of foot eczema using patch test. Clin Dermatol Rev [serial online] 2020 [cited 2020 Oct 26 ];4:149-154
Available from: https://www.cdriadvlkn.org/text.asp?2020/4/2/149/292483


Full Text



 Introduction



Foot eczema implies to predominant and exclusive involvement of feet in eczematous reaction. It is a common condition seen in dermatology clinics which poses a challenge to the clinician to find the causative agent. It causes pain and discomfort to the patient due to its chronic course and more frequent recurrence rate.

It often gets difficult to completely abolish the eczema as the allergen remains unknown. Patients may have sensitivity to one or the other ingredient present in the footwear itself. Allergy, atopy, occlusion due to footwear, humidity, and sweating can also contribute to the eczematous process of shoe dermatitis.[1]

In most of the cases, foot eczemas are empirically diagnosed without pinpointing the contributory allergens by allergic patch testing and hence lead to recurrences, and the patients are usually sensitive to more than one ingredient of the footwear; hence, it gets difficult to know which footwear is best avoided.

We also note that history alone may not be reliable in pinpointing the incriminating antigens in the footwear dermatitis as the same person may be using multiple types of footwear and some of the modern footwear tend to be made of combinations of various materials.

There is a paucity of studies showing patch tested patients from India for footwear dermatitis In our study, we aim to know the frequency of foot eczemas which are due to footwear dermatitis and to find the most common ingredient in the footwear which acts as an allergen in causing foot eczema.

Avoiding the footwear containing the allergen can give a complete remission of eczematous process and aid in prompt treatment with better prognosis.

 Materials and Methods



Aims and objectives of study

To find the role of footwear as a cause of foot eczema using patch testing for Indian footwear seriesTo find the most common allergen in the footwear causing foot eczema by patch testing using Indian footwear series.

Study population

A total of 70 patients with foot eczema satisfying inclusion and exclusion criteria attending outpatient department of Father Muller Medical College Hospital, Kankanady, Mangalore.

Study period

The total study duration was from September 2016 to March 2018.

Inclusion criteria

Patients with exclusive foot eczema willing for the patch testingPatients above 15 years of age.

Exclusion criteria

Patients not willing for the patch testPregnant and lactating womenAcute eczema with secondary infection of feetPatients taking oral immunosuppressive agents such as steroids and other steroid-sparing agents within the past 2 weeks.

Sample size - A total of 70 patients (P = 0.2422)[2]

Error (e) as 10% and zα as 1.96 at 95% confidential limit

n = zα2p(1-p)/e2

= (1.96)2 (0.2422) (1-0.2422)/100

= 70

Study design

Hospital-based descriptive study

Approval taken from the institutional ethics committee was obtained. Written informed consent was taken from seventy patients who were included in the study.

Methodology

The subjects were asked for detailed history about the age, occupation, site of lesion, associated symptoms, progression, duration of disease, recurrent episodes, seasonal variation, aggravating factors, history of recent change of footwear, type of footwear used, history of atopy, and history of taking medications for the same. Morphology and distribution of lesion over feet were examined.

Foot eczema was diagnosed by physical examination, relevant investigations such as skin scrapings for KOH mount to exclude dermatophyte infections, and skin biopsy wherever needed were performed.

All patients satisfying the inclusion and exclusion criteria were included in the study. Patients were asked to discontinue ongoing oral antihistaminics 48 h prior to the patch test to avoid false-negative results or decreased intensity of reactions.

Informed written consent was taken from all patients above 15 years willing for the patch testing.

Back was chosen for the application of tests. Hair was shaved using a razor blade in subjects with excessive body hair. Area was degreased and wiped till dry. Patients will be subjected to patch testing using Indian footwear series containing 15 allergens which are manufactured by Creative Diagnostic Medicare Pvt. Ltd. and approved by “Contact and Occupational Dermatoses Forum of India” including the following allergens – formaldehyde, mercaptobenzothiazole, potassium dichromate, Kathon CG, nickel sulfate, colophony, Epoxy resin, neomycin sulfate, hydroquinone, thiuram mix, black rubber mix, glutaraldehyde, dioctyl phthalate, disperse orange, and disperse blue.

Allergens were marked using a pen over the adhesive tapes. Date and time of test done is noted. A patient was instructed to avoid wetting his back or performing any activity that led to excessive sweating and loosening of patch. They were also advised to wear loose clothing and avoid scratching the back. After the test, the patient was called after 48 h and the reading was taken after 30 min of removal of patch. Reaction will be read and graded using the International Contact Dermatitis Research Group guidelines [Table 1].{Table 1}

Patch test positivity, most common allergen, sex preponderance, most common age group affected, occupation, and type of skin lesions will be noted.

Statistical analysis

Data were collected, coded and entered into Microsoft Excel spreadsheet and analyzed using the Statistical Package for the Social Sciences (SPSS) version 20 for Windows.

Data were analyzed for statistical significance by Chi-square test for categorical data.

P < 0.001 was considered statistically significant.

The causative agent in foot eczema is identified by risk rates.

Results were expressed in frequency, percentage, mean and standard deviation.

 Results



Among the patients studied, the age group ranged from 13 years to 70 years. The mean was 31.96. Duration of disease varied from 3 months to 10 years, the mean being 3.15.

Majority of the patients in this study belonged to the age group 12–40 years comprising a total of 78.85% [Table 2].{Table 2}

Out of 71 patients enrolled in the study, 44 (62%) were females and 27 (38%) were males. Male-to-female ratio was 1:1.6 [Table 3].{Table 3}

Plantar surface of foot was the most common site involved, constituting 35.2%, followed by dorsum of foot (29.6%) and forefoot (20%). The least common sites involved were heel (2.8%) and instep of foot (4.2%) [Table 4], [Figure 1] and [Figure 2].{Table 4}{Figure 1}{Figure 2}

Seasonal variation was noted in 39.43% of the patients, with winter season being the aggravating factor in 21.1% of patients, followed by summer in 12.7% patients. 60.6% patients showed no seasonal variation [Table 5].{Table 5}

Footwear was the most common aggravating factor as reported by the patients in 23 (32.4%) patients (P value 0.013) which is statistically significant. A total of 46.5% patients reported spontaneous onset or no aggravating factor [Table 6].{Table 6}

History of atopy was present in 35 (49.3%) patients and was absent in 36 (50.7%) patients, with 51.42% and 48.57% patients showing personal and family history of atopy [Table 7], respectively (P = 0.687), which is not statistically significant.{Table 7}

A total of 45 patients showed positive patch test out of 71 patients who were tested, accounting 63.4%. This indicates that footwear is significantly one of the main causes for foot eczema among the patients attending the dermatology clinics. Majority of the patients did not report any aggravating agent in the causation of eczema, however, 14 out of 33 patients were tested positive for one or more allergens. Among 23 patients who gave a history of footwear induced dermatitis, 19 were tested positive (82.60%).

Fifty-five patients were diagnosed clinically as allergic contact dermatitis and 16 were diagnosed as nonallergic contact dermatitis. Forty patients out of 55 were tested positive for patch test (true positives) and 15 were tested negative (false negative). Five out 16 patients of nonallergic contact dermatitis were tested positive for foot eczema (false positives) and 11 out of 16 were tested negative for patch test (true negatives) [Table 8]. Hence, the sensitivity and specificity of patch test for allergic contact dermatitis were found to be 72.72% and 68.75%, respectively, with a positive prediction value of 88.88% and negative prediction value of 42.30%. Hence, patch test is a useful diagnostic tool for diagnosis of allergic contact dermatitis due to footwear (P = 0.012).{Table 8}

Black rubber mix was the most common sensitizer noted in our study (22.53%), followed by nickel (14.08%) being the second most common sensitizer. Footwear of women are more trendy and studded with various metallic fittings and buckles. This could be a reason for increased eczema due to metals not just on the foot but also over other sites of body. The 3rd most common sensitizer noted in our study was colophony accounting 12.67%. Colophony is found in shoe adhesives, as a tackifier in the rubber that is used for sole attachment or for attaching the layers below the insole. Other sensitizers found included mercaptobenzothiazole (9.8%), potassium dichromate (9.8%), and Thiuram mix (8.45%). Three patients showed positivity to neomycin which is a topical antibacterial medicament.

 Discussion



Patch testing is a simple diagnostic test performed in an outpatient basis which is an important tool of the dermatologist to evaluate patients with chronic cutaneous eruptions. This simple test helps to determine the delayed hypersensitivity reaction to various allergens causative of dermatitis. Patch test helps the patient to know the exact etiological agent in the causation of eczema and aids in avoidance of those allergens. Many a times, eczema mimics other dermatoses like psoriasis. In such situation, patch test becomes a useful diagnostic tool for prompt treatment of skin diseases.

Patch testing is the only scientific method to detect the cause of contact dermatitis. A good patch test must indicate contact sensitization; produce no false-positive reactions; the allergens should be pure and in the right concentration; the risk of active sensitization should be low; there should be minimum irritant reactions; and it should be stable, easy to apply, and read and suitable to the patient.

The study was conducted in a coastal tertiary hospital with the aim to find the role of footwear as a care cause of foot eczema. Our study included a total of 71 patients in the age group of 12–70 years. The most common age group of patients in this study was 12–40 years. This indicates that sensitivity to the allergens is greater in the younger age groups comprising a total of 78.85%. Most of the patients in this age group are working class and hence increased exposure to footwear and often tend to change footwear more frequently. Women tend to use fancy footwear containing metallic fittings and buckles which could be the reason for increased foot allergies. The number of patients in the older age groups (41–70 years) constitutes a less proportion of study subjects. These results are in accordance with the study conducted by Suryanarayana et al.[3] and Priya et al.[4] However, a study conducted by Chowdhary.[2] had most number of patients in the age group of 41%–50%.

Females outnumbered the males in this study with a ratio of 1.6:1. This could be due to the increased household activities in females including contact with detergents and cleansing agents which causes irritant dermatitis and impairs barrier function of epidermis facilitating the easy penetration of allergens in footwear and also due to using footwear with mixed allergens and fancy fittings to match the wardrobe. This is in accordance with study conducted by Priya et al.[4] and Chowdhary[2] whose study also showed a female preponderance and against the study conducted by Suryanarayana et al.[3] who showed a male preponderance.

The most common site of involvement of eczema in our patients was plantar aspect of foot accounting to 35.2% probably due to the allergens present in the sole of the footwear, followed by dorsum of foot (29.6%). A study conducted by Priya et al.[4] and Handa et al.[5] showed that the most common site of involvement was dorsum of the footwear corresponding V-shaped chappals. A study done by Brar et al.[6] showed that the most common site of affection was plantar surface of toes (38.09%) which is similar to our study. The mean duration of disease observed in our study was 3.15 years.

Personal and family history of atopy was present in 35 out of 71 patients, and 23 of these 35 patients showed a positive patch test result for footwear series. Results are compared with study conducted by Ebstein et al.[7] where 12 out of 43 patients showed the past and present history of atopic eczema. However, a study by Brar et al.[6] showed no significant association with atopy in their study.

The most common aggravating agent reported was footwear in 23 out of 71 (32.4%), followed by cement, detergents, and metals accounting 5.6%, followed by detergents (4.2%). Nineteen out of 23 patients of footwear allergy were tested positive to one or more footwear allegens using patch test. A study conducted by Suryanarayana et al.[3] showed the highest patch test positivity in construction workers (14 out of 30 workers) who are exposed to cement, followed by mechanic, woodworkers, and housewives. Fifteen out of 71 patients (21%) gave history of aggravation of lesions in winter and 9 patients (13%) in summer. The earlier studies have showed an aggravation in summer probably due to increased sweating and friction in the closed shoes, however, atopics may show an aggravation in winters. A study conducted Priya et al.[4] in coastal Karnataka in 2006 also showed aggravation in winters.

Out of 71 patients enrolled in our study, 45 patients (63.4%) showed positivity to patch test for one or more allergens [Figure 3] and [Figure 4]. A study by Sreejesh Narayana et al.[8] and Chowdhari et al.[2] showed 29% and 24% patch test positivity for footwear, respectively. A study by Suryanarayana et al. showed 60% positivity to patch tests which is in accordance with our study. Black rubber mix was the most common sensitizer noted in our study (22.53%), followed by nickel (14.08%) being the second most common sensitizer. The 3rd most common sensitizer noted in our study was colophony accounting 12.67% [Table 9]. Other sensitizers found included mercaptobenzothiazole (9.8%), potassium dichromate (9.8%), and Thiuram mix (8.45%). Three patients showed positivity to neomycin which is a topical antibacterial medicament.{Figure 3}{Figure 4}{Table 9}

Our study is in accordance with studies conducted by Freeman et al.,[9] Warshaw et al.,[10] and Handa et al.[5] who showed that rubber was the most common sensitizer accounting 44% and 40%, respectively. A study conducted by Chowdhari et al.,[2] Saha et al.,[11] and Suryanarayana et al.[3] showed potassium dichromate to be the most common sensitizer present in leather footwear. A study by Priya et al.[4] showed mercaptobenzothiazole to be the most common sensitizer.

 Conclusion



Patch test plays a major role in identifying the role of footwear in the causation of eczema as evidenced by the statistically significant positivity of patch tests, with black rubber, nickel, and colophony being the major allergens which are present in the footwear. It is a safe, simple, and useful diagnostic tool to identify the specific allergen.

Displaying of the chemicals used in the material of the footwear if made mandatory would benefit those people suffering from foot eczema, which unfortunately is not statutory as of now.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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