Programme for prevention of foot dermatoses in patients with work‐related skin diseases: Baseline data and first results of a prospective cohort study (OCCUPES)

Programmes for prevention of hand dermatoses in patients with work‐related skin diseases (WRSD) are well established. Similar interventions for foot dermatoses (FD) are widely missing.


| INTRODUCTION
Even though work-related skin diseases (WRSD) are primarily located on the hands with hand eczema being the most common skin disease acquired at work, 1 other body parts can be affected, including the feet.
WRSD of the feet could be related to direct exposure to skin hazards at work due to insufficient protection by footwear or the footwear itself, causing, for example, irritant or allergic contact dermatitis. Prolonged standing, carrying heavy loads and walking for long distances might be contributing factors. Moreover, WRSD of the hands can be accompanied by skin diseases of the feet not related to work. Therefore, differentiation between occupational and non-occupational causes and weighting of their respective impact is often challenging in foot dermatoses (FD).
So far, studies on the prevalence of foot eczema and other FD, including fungal infection and plantar psoriasis, are scarce in patients with WRSD. Not much is known about related factors and there is a lack of tailored prevention strategies. Previously, we demonstrated that about one third of 843 consecutive patients taking part in a tertiary individual prevention programme (TIP) for WRSD had FD. 2 The most frequent FD was foot eczema (n = 208, 24.6%). Among all patients with hand eczema (n = 723), 201 (27.8%) had concomitant foot eczema which was significantly associated with male sex, atopic hand eczema, hyperhidrosis, tobacco smoking and wearing of safety shoes/boots at work. An occupational irritant component of concomitant foot eczema was suspected in nearly 20% of these patients. Similarly, it was demonstrated that 28.9% of metalworkers with WRSD participating in the TIP had foot eczema 3 and a European crosssectional multicentre study showed that about one quarter of 419 patients with hand eczema (regardless of origin) suffered from concomitant foot eczema. 4 In Germany, a multi-step intervention approach funded by the statutory accident insurance has been established to reduce the burden of WRSD. [5][6][7] It is mainly directed at prevention of WRSD affecting the hands, but is covers also patients with WRSD of other body parts. Apart from outpatient treatment and diagnostics, patients with early or mild symptoms of WRSD are offered to participate in a secondary individual prevention programme (SIP) which usually involves an interprofessional outpatient skin protection seminar with emphasis on health education. 7 Patients with severe WRSD refractory to secondary prevention measures are invited to take part in the inpatient/ outpatient TIP which combines intensified treatment and health education. 7,8 Both, the secondary and tertiary prevention measure have been shown to be beneficial in terms of reducing the severity of hand dermatoses and improving the ability to work. 7 Nothing, however, is known about their efficacy in skin diseases of other body parts.
In the past years, we have developed and established a programme for prevention of FD in our department which is offered to patients with WRSD who suffer from FD and take part in secondary or tertiary prevention measures. We conducted a prospective cohort study (OCCUPES) to evaluate the effectiveness of this programme, while investigating the impact of FD and possible causative factors.
Here, we present the baseline results.

| Intervention
The programme consists of a training on prevention of FD which is provided during the TIP or in an outpatient setting, either embedded in the regular SIP seminar or as a separate outpatient individual faceto-face FD counselling (FD-SIP). Key recommendations provided in the training are presented in Table 1. Some of them are based on common recommendations for prevention of hand eczema. 9,10 The SIP is offered to patients with suspected WRSD shortly after notification of the statutory accident insurance institution. The detailed set-up of the regular outpatient two-day SIP at the study centre in Osnabrück has been described before. 11 13 The study protocol was approved by the ethics committee at the Osnabrück University.

| Assessments
Assessments by structured interviews based on questionnaires mainly comprising closed questions were carried out at baseline. Basic Index (OHSI) 16,17 to assess the severity of the FD according to the extent of areas affected by eight morphological signs. For this score, the foot is subdivided into six areas and for each area the presence of eight morphological signs is recorded. One point is given for each area affected by a single sign. The occurrence of skin signs is counted separately for both feet resulting in a total score ranging between 0 and 96 points ( Figure S1). Health-related quality of life was assessed with the Dermatology Life Quality Index (DLQI). 18 The DLQI has a score range from 0 to 30 and the higher the score, the more quality of life is impaired. The patients were asked to focus on impairments related to the FD when filling out the DLQI questionnaire. Separate Visual Analogue Scales (VAS) were used to assess the intensity of itch and pain caused by the FD within the past 24 h. A straight 10 cm line without demarcation that had anchor statements on the far left (0 cm: either 'no pain' or 'no itch') and the far right (10 cm: either 'the most intense pain imaginable' or 'the most intense itch imaginable') was presented to the patients. They were asked to place a mark at the point on the line corresponding to the patient's rating of pain/itch intensity. The distance of that mark from the far left was measured in centimetres and then used as continuous variable. In TIP patients, a second assessment (OFSI, DLQI, VAS) was done shortly before dismissal (T2), that is, 3-4 weeks after baseline.
Six months (T3) and 1 year (T4) after recruitment, the patients received questionnaires covering similar items than at baseline. The results of these follow-ups will be presented in a separate publication.

| Statistics
Statistical analyses were conducted with SPSS Version 25.0 (IBM

| Occupational footwear
The characteristics of occupational footwear are presented in Table 3.

| FD in general
The diagnosed FD are presented in Table 4. The majority (n = 175, 75.8%) suffered from foot eczema which consisted of more than one subtype in 28.0%. The most common subtype was atopic foot eczema Other characteristics of the FD are presented in   (Table 6).  considered work-related (Tables 2 and 3). Work-related FD was more severe based on the OFSI ( p = 0.056) and significantly more often associated with itch (p = 0.018), pain when walking (p = 0.006) and
Work-related allergic contact dermatitis of the feet was diagnosed only in seven patients (11.7%), of which four had sensitisations to chromium, three to benzothiazols, two to p-tert-butylphenol formaldehyde resin (PTBP-FR) and one to thiurams, and one to colophonium. Rare causes of work-related FD were irritant worsening of Often mixed diagnoses consisting of work-related and not work-related components occurred in the same participant. Presented is how often a diagnosis was considered work-related in relation to the frequency of the same diagnosis in all participants. b More than one subtype possible.
T A B L E 5 Other characteristics of foot dermatoses of all participants at baseline, including comparison of those without and with work-related foot dermatosis.

| Wearing of safety footwear
There were significantly more men among the 168 patients wearing safety footwear at work than among those wearing other types of footwear ( p < 0.001) ( Table S2)

| Sweating in occupational footwear
There were significantly more men among the 145 patients reporting sweating in occupational footwear than among the other patients (p < 0.001) (Table S3). Sweating was associated with younger age ( p < 0.001), wearing safety footwear ( p < 0.001), metal work It is striking that a work-related course of FD was reported three times more often by the patients than had been documented in the patients' files provided by the respective statutory accident insurance institutions which mainly consisted of reports about the WRSD regularly submitted by the treating dermatologists at home. 19 This indicates underreporting of potentially work-related FD in these patients.
As isolated FD was rare, it has to be considered that the dermatologists had focused on the hand dermatosis as the relevant WRSD neglecting the feet or negating the possibility that FD could be workrelated and as such being not worth documenting for the statutory accident insurance institutions. In about one quarter of the patients, an at least partially work-related cause of the FD was finally considered likely which is similar to the proportion reported in our previous study. 2  to do so because they reported to have a second pair of shoes/ boots at work. Changing socks during one shift was even less common in these patients. Even though there was, thus, substantial room for improvement which was addressed in the training, changing to a second pair of footwear and changing socks during one shift were already significantly more common in those with work-related FD compared to those without, suggesting that preventive measures addressing sweating in footwear had already been implemented in some of these patients. Only few patients (<10%) who complained about sweating in footwear reported treatment with tap water iontophoresis or topical antiperspirants within the previous 12 months indicating another missed chance of decreasing moisture built in footwear in many of these patients.
Work-related FD was additionally associated with male sex and wearing of safety footwear which is compulsory in many occupations with a male predominance (e.g., metal and construction work, warehouse work and gardening). In contrast, the female-dominated nursing profession, in which no safety footwear is worn and other hazardous exposures of the feet are rare, was significantly less frequent among those with work-related FD. As expected, safety footwear seems to protect very well against direct exposure to wetness and cold feet which was significantly more often reported by those not wearing safety footwear. Instead, sweating was significantly more common in those wearing safety footwear. Similarly, wearing safety footwear at work was significantly associated with foot eczema in patients with hand eczema in our previous study, especially in those who reported sweating in safety footwear. 2 The evaporation capacity of safety footwear varies greatly depending on its materials. For some work tasks (e.g., welding) wearing of completely closed safety footwear is mandatory. For many occupations, however, modern safety footwear equipped with breathable and moisture-wicking materials is available, even for most wet work tasks (e.g., footwear with semipermeable Gore-Tex ® membranes).
To enable efficient permeation of moisture to the outside, this footwear must be worn in combination with functional socks made of breathable and moisture-wicking fibres. Despite this, only a small minority of those wearing safety footwear reported to wear functional socks. Socks with a high cotton content do not provide this function, but rather trap the moisture and should be worn with footwear made of pure leather or occlusive materials (e.g., rubber) instead. The importance of selecting socks matching to the type of footwear was addressed in the training and in the subsequent individual recommendations representing another opportunity for improvement in this cohort.
Allergic contact dermatitis of the feet was rarely diagnosed and related to allergens in footwear. 23 As in the previous study, 2 an additional shoe series was not patch tested in all patients which may have led to an underestimation of the true number of patients with allergic contact dermatitis of the feet. However, allergic contact dermatitis is in general less commonly located on the feet than on the hands. 24 Even though, allergic contact dermatitis of the feet is rare, patch testing is still very important in patients with foot eczema as detection of sensitizations to typical shoe allergens (e.g., chromium) should prompt selection of specific footwear to enable allergen avoidance (e.g., leather-free footwear or footwear made of chromium-free leather).
Reporting tobacco smoking and an extensive daily cigarette consumption was very frequent. This is in line with findings from other studies showing that the share of smokers and the cigarette consumption is high in patients with WRSD, particularly in TIP patients. 3,25 It has been demonstrated that tobacco smoking is related to severity of hand eczema, concomitant foot eczema and a worse prognosis in TIP patients. 2,25 In this small cohort, we could not find a significant association between severity of foot eczema and tobacco smoking or extent of cigarette consumption.
There are several strengths and limitations of our study. The patients were investigated by trained dermatologists taking thorough histories based on structured interviews and assessing the aetiology of the presented skin diseases. However, self-reported data is potentially unreliable in some cases. Moreover, the associations we have found may, in principle, represent the effect of other unmeasured individual factors and confounders. The OFSI has yet not been validated for assessing the severity of foot eczema/FD. However, it correlated very well with the DLQI and the VAS for both itch and pain, stressing its value.
In conclusion, the burden of FD in patients with WRSD is consid-

CONFLICT OF INTEREST STATEMENT
The authors declare no conflicts of interest.

ACKNOWLEDGEMENT
Open Access funding enabled and organized by Projekt DEAL.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.