Section 4.1 Allergen Series and Deciding What to Test

Organisation of allergens and series

When embarking on the patch testing process, there are several things to note when ordering allergens. Firstly, there are many many many allergens which are grouped into series. These series assist dermatologists to decide what to test, and make allergen selection faster, easier and more comprehensive.

For example, allergens listed in the hairdressing chemical series contain the most likely causes of dermatitis resulting from hairdressing chemicals. So if a hairdresser or a person who uses hair dye develops a rash suspicious for contact dermatitis, this series could be used to help diagnose this condition. There is also a hair products series that can be helpful if many hair products are used.

The series that are currently available at the Skin Health Institute, Melbourne are listed in attachment or for CABA users www.patchcams.asn.au

Please note the sunscreen series is split into two sunscreen series and sunscreen separates. The sunscreen separates refers to the allergens that need to be exposure to UVA. See Section 6.2 Patch Application for further information.

The Australian Baseline Series

The First Australian Baseline Series was created in 2012 and represents the 60 most prevalent, current, locally relevant and important patch testing allergens for patients being patch tested in Australia, providing a comprehensive screen for the diagnosis of allergic contact dermatitis. The team at the Skin Health Institute, Melbourne developed their own standard series of allergens which was based on local clinical research and is reviewed every 3 years (last reviewed in 2021).

The Australian Baseline Series was developed with the following considerations:

• The most relevant and common patch test reactions
• Emerging contact allergens
• Allergens that are important not to miss, such as those in medicament creams
• The need for a comprehensive series due to limited access to individual allergens/specialized series outside of sub-specialist patch testing centres
• Possible referral biases

Dermatologists around the world traditionally use a baseline series, previously known as a ‘standard’ series of allergens, which represent the core allergens used to evaluate every patient undergoing patch testing. In specialised clinics, this is supplemented by other series or individual allergens, based on the patient’s occupation and history of exposures.

The baseline series should ideally contain the most common contact allergens in the population being patch tested. It is therefore understandable that the baseline series will vary across centres, reflecting regional differences in allergen exposures and the threshold chosen for testing. The European Standard Series, North American Contact Dermatitis Group series and Mayo Clinic standard series are some examples.

Almost all patients that attend the Skin Health Institute, Melbourne are tested with the ABS, plus additional personalised tests added to this baseline series and their own product samples.

The Australian Baseline Series (ABS) as of February 2022

Which series to test?

To assist with allergen and series selection we have developed information sheets recommending key allergens/series to test depending on the occupation or rash location. See attachment

For example, we would suggest that a patient that has foot dermatitis be tested to the Australian Baseline Series and shoe series, with key allergens being potassium dichromate (used in the tanning of leather, relevant to leather shoes), and Basic Red 46 which is a textile dye used in cheap, dark coloured thick style sock. The shoe series also contains other rubber allergens that are often used in shoe manufacture.

Another common example is a healthcare worker, who should be tested to the Australian Baseline Series, rubber series, and nurses’ baseline series, with key allergens including preservatives and fragrances often used in hand cleansers, rubber accelerators used in gloves, chlorhexidine and antiseptics. Latex allergy should also be tested in any healthcare worker who uses latex gloves (at home or at work). This can be done by a blood serum test (formerly a RAST), or an allergist may use prick testing.

N.B Latex blood test should be considered for anyone wearing latex or rubber gloves, regardless of their job description.

Recommended Reading

2015 Toholka R, Wang Y-S, Palmer A, Nixon R. The first Australian Baseline Series: Recommendations for patch testing in suspected contact dermatitis. Australas J Dermatol 2015; 56: 107-15

2020 Dear K, Bala H, Palmer A, Nixon RL. How good is the Australian baseline series at detecting allergic contact dermatitis? Australas J Dermatol. 2021 Feb;62(1):51-56. doi: 10.1111/ajd.13456. Epub 2020 Sep 11. PMID: 32914863.

2020 Felmingham C, Davenport R, Bala H, Palmer A, Nixon R. Allergic contact dermatitis in children and proposal for an Australian Paediatric Baseline Series. Australas J Dermatol. 2020: 61:33-38 doi: 10.1111/ajd.13169.

Videos to watch:

Talk 5-8 Understanding the ABS

Talk 9 When the ABS isn’t enough

Talk 34 When the ABS isn’t enough – occupational cases

Talk 12-13 Preservative allergy

Talk 14 Deciding what to test

Talk 10 Patient counselling and selecting allergens

Talk 16 + 20 -26 Lectures regarding approach to diagnosis for particular sites