Foot ulcers among diabetics are common. In 2015, around 20,000 patients in the Netherlands
had a diabetic foot ulcer.1 A study using data from Dutch general practices found a
prevalence rate of 0.50% and a 4-year prevalence rate of 2.85%.2 For Europe, Zhang et al.
estimated a pooled prevalence of 5.1% (95%CI: 4.1-6.0%).3 Prevalence rates increase with age.
The underlying mechanism of diabetic foot ulcers is most often solely neuropathy (60 to 70%),
15 to 20% have peripheral artery disease (PAD) only, and 15 to 20% have a mixture of both.4
Diabetic foot is more prevalent in males and more prevalent in type 2 diabetes than in type 1
diabetes3. Ulcers in patients without diabetes are mostly caused by venous insufficiency.5
Ulcers have a slow healing tendency. Around 15 percent of diabetic patients with an ulcer
eventually have to amputate (a part of) the leg.1 Good wound care is therefore important.
However, wound care can be delayed in the presence of a contact allergy. Contact allergy
(synonym for contact sensitivity) is defined as an altered immune status of an individual
induced by a particular sensitizing substance, a contact allergen. An individual in whom
contact allergy has been induced will develop a secondary immune response if there is skin
exposure to the same (or cross-reacting) allergen. This process is called elicitation, and
will manifest as allergic contact dermatitis (type IV hypersensitivity).6 Allergic contact
dermatitis, also termed allergic contact eczema, is defined as an inflammatory skin reaction
caused by direct contact with noxious agents in the environment as a result of contact
allergy.
Among patients with venous leg ulcers contact allergies is seen in around 50 percent of which
10-20% for wound dressings.7-10 The prevalence of contact allergies is getting higher and
also increasing with the duration of the ulcer. 8,10 Wound dressings can cause allergic
contact eczema (allergic contact dermatitis).
At present, the prevalence of contact allergies for wound dressings in diabetic patients with
foot ulcers is unknown. With this study we want to gain insight in the prevalence of contact
allergies in patients with diabetic foot ulcers and investigate if the prevalence of contact
allergies among diabetic patients is as high as the prevalence in patients with venous leg
ulcers.
Objective of the study:
The primary objective of this study is to determine the prevalence of contact allergies in
patients with diabetic foot ulcers.
Study design:
This is a prospective, multi-centre study.
Study population:
The study population are high risk diabetic patients with a foot ulcer visiting the
multidisciplinary consultation hour for diabetics at the clinic.
Diabetic patients are patients diagnosed with type 1 or type 2 diabetes.
Primary study parameters/outcome of the study:
The presence of contact allergy for wound dressings
Secundary study parameters/outcome of the study (if applicable):
The following factors will be gathered at baseline:
Age
Gender
Diabetes type
Duration of diabetes
Medication use
Ulcer characteristics like type, size, duration, progress (TEXAS classification)
Number of past foot ulcers
Duration of past foot ulcers
Known allergies or atopy constitution
Presence of allergic contact dermatitis around the wound
Doses corticosteroid or antihistaminic therapy (not during PATCH testing)
History of eczema
Parameters to define if there are other mechanisms besides diabetics underlying the ulcer:
Ankle brachial index , toe pressure measurement or Transcutaneous oxygen pressure
(TcPo2)
Venous insufficiency which is measured by a venous duplex, if applicable
Parameters related with contact allergy or parameters that can influence the development of a
contact allergy:
Known allergy. If yes, which allergy/allergies?
Duration of current ulcus cruris
Number of past ulcers
Treatment with wound dressing(s) current episode:
Treatment with wound dressing(s) prior episode(s)
Prevalence of allergic contact dermatitis
Nature and extent of the burden and risks associated with participation, benefit and group
relatedness (if applicable):
Not applicable