Recommendation to update the British Society for Cutaneous Allergy corticosteroid series.

Background: Patch testing is an important investigation when dermatitis is unresponsive to, or worsened by, topical corticosteroid treatment. There is a balance to be struck between testing too many allergens, which is expensive, time consuming and risks causing sensitization, and testing too few, which risks missing the diagnosis. The current British Society for Cutaneous Allergy (BSCA) corticosteroid series comprises eight allergens and was last updated in February 2007.

Aim: To review and update the BSCA corticosteroid series.

Methods: We retrospectively analysed data from 16 patch test centres in the UK and Ireland for all patients who were patch tested to a corticosteroid series between August 2017 and July 2019. We recorded the allergens tested, the number and percentage tested to a corticosteroid series and the number of positive results for each allergen. We identified the allergens that test positive in ≥ 0.1% of selectively tested patients.

Results: Overall, 3531 patients were tested to a corticosteroid series in the 16 centres. The number of allergens tested ranged from 7 to 18 (mean 10). The proportion of patch test patients who were tested to a corticosteroid series ranged from 1% to 99%. Six allergens in the 2017 BSCA series tested positive in ≥ 0.1% of patients. Nine allergens not in the BSCA corticosteroid series tested positive in ≥ 0.1% of patients.

Conclusion: This audit demonstrates the importance of regular review of recommended series and the significant variations in practice. The new BSCA corticosteroid series that we recommend contains 13 haptens, with the addition of the patient's own steroid creams as appropriate.