Contact Dermatitis to Ophthalmic Solutions: An Update.

Eyelid and periorbital dermatitis remains a distressing and recalcitrant disease. Contact dermatitis remains the most common cause of eyelid and periorbital dermatitis. Ophthalmic solutions used in the treatment of ophthalmic conditions can often be the cause. This article is an update of our previous study, summarizing the contact allergens involved and the new test concentrations reported to investigate through patch testing. New insights found during the review are also documented.

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.

Ideal proportion of the population to be patch tested: How many should we be doing?

BACKGROUND: How many patients should we be patch testing? A previous study suggested that the minimum proportion of a population to be patch tested for allergic contact dermatitis was 1:700 annually. OBJECTIVES: To evaluate if the current minimum rate for patch testing has changed over the 20 years since the previous study in order to maximize the value. METHODS: In cooperation with the British Society for Cutaneous Allergy, a proforma for collation of retrospective data between January 2015 and December 2017 was sent to patch-test centers in the United Kingdom (UK) and the Republic of Ireland (ROI). The number of positive tests was analyzed against the proportion of population tested to see what proportion of the population would yield the greatest number of positive results. RESULTS: Responses from 11 centers showed that the minimum number needed to patch test had increased to 1:550 per head of population per year using the current criteria. CONCLUSIONS: In agreement with previous studies, we should be patch testing more people than we are. We could reduce the threshold for referral of patients we patch test to derive the most benefit from this investigation.

National survey of patch testing in the United Kingdom and Republic of Ireland: what proportion of the population is and should be tested?

BACKGROUND: An initial study of patch testing practices across Wales, United Kingdom, showed wide variation in practice against a standardized set of guidelines and best practice recommendations. OBJECTIVES: To evaluate (i) current patch testing practice on a national level in the United Kingdom and Republic of Ireland (ROI), (ii) compliance with the current published guidelines, and (iii) the proportion of the catchment population tested by patch testing centres. METHODS: In consultation with the British Association of Dermatologists and British Society for Cutaneous Allergy, proformas addressing clinical guidelines and best practice recommendations were sent to all dermatology units in the United Kingdom and ROI. RESULTS: Ninety one of 325 centres (28%) performed patch testing. The optimum proportion of annual tests was not being achieved in the United Kingdom and ROI. The range tested varied between 1:1200 and 1:1600. CONCLUSIONS: Most centres achieved a high level of best practice outcomes. Shortcomings were found in the recording of minimum data, benchmarking, and attendance at meetings. We suggest that the findings of this study should be used as evidence to help improve services locally.

The relationship between the proportion of the population tested annually and the rate of patients with positive patch test reactions.

BACKGROUND: Differences exist between the rates of patients with positive patch test reactions in different centres. OBJECTIVES: To explore the varying relationship between the percentage of patients with one or more positive reactions (rate of patients with positive reactions) and the proportion of the population tested annually (intensity of testing) by UK centres contributing to a shared data pool. METHODS: Patch test data were pooled from 11 UK centres that use the British Society for Cutaneous Allergy (BSCA), formerly known as the British Society for Contact Dermatitis, database. The catchment population size was estimated for each centre, and the rate of patients with positive reactions to allergens in the BSCA baseline series was calculated. RESULTS: As the intensity of testing increases, the rate of patients with positive reactions decreases. We found a strong linear correlation in the range of interest between the intensity of patch testing and the proportion of tests returning a positive result (R(2) = 0.598). CONCLUSION: Within the range of testing intensities covered by our reporting centres, the data show that as the intensity of testing increases, the rate of patients with positive reactions decreases.