Patch Test (medicine) - Setting Up A Service

Setting Up A Service

Setting up a patch testing service is a time consuming process (see below) and takes up three clinic spaces a week for each patient. It is useful to know how many patients are likely to be seen and how useful the testing will be to pick up positive results. Studies have shown that the optimum number of patients to be tested is 1 in 700 of a population. So in a population of 70,000, 100 patients should be tested annually to detect contact allergy.

Coupled with this, differences exist between the rates of positive reactions to the patients tested in different centers. Effectively, the greater the proportion of the population tested for contact allergy, the lower the proportion of positive outcomes identified. When setting up a service, it is important to know what impact it will have on the population.

The British Association of Dermatology has set guidelines for patch testing within the UK which state that a patch test service needs:

• A named lead dermatologist for the unit who has received training for at least 6 months at a recognized contact dermatitis investigation unit or who can demonstrate comparable experience.
• That the contact dermatitis investigation unit conforms to best practice guidelines. The unit and the staff should
  • Have a dedicated investigation clinic which should include an area for storage (refrigerator) and preparation of allergens.
  • Record investigation results on an electronic database with a minimum data set: site of onset of dermatitis and duration; gender, occupational, atopy, hand dermatitis, leg dermatitis, face dermatitis and age index; details of occupation and leisure activities; patch test results including type (allergic/irritant) and severity of reaction; relevance of positive tests, occupational or otherwise; and final diagnosis.
  • Participate in regular audit of data and ‘benchmarks’ results with nationally pooled data. This is evolving and will be reviewed periodically.
  • The lead dermatologist demonstrates regular attendance at CME-approved update meetings on contact dermatitis (at least every 2 years).
  • The unit should have up-to-date reference textbooks on contact dermatitis including occupational dermatitis and relevant journals.