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.

UK trends of allergic occupational skin disease attributed to fragrances 1996-2015.

BACKGROUND: Fragrances are well known to cause allergic contact dermatitis (ACD). Occupationally related cases occur, with certain groups being at higher risk. OBJECTIVE: To investigate the incidence of occupationally related cases of cutaneous fragrance allergy and to evaluate trends. METHOD: Data on incident cases of occupational ACD caused by fragrances between 1996 and 2015 (inclusive) reported to the EPIDERM surveillance scheme were analysed. RESULTS: Of the cases reported to EPIDERM during the study period, 5.2% had ACD attributed to fragrances. The highest annual incidence rates were observed in women. Hairdressers, beauticians and people working in related occupations had a 47-fold higher incidence rate ratio than the reference category (the average of all other occupations combined). Trends analysis suggested a non-significant increase in fragrance allergy over the study period among all occupations, and beauty and food workers, and a slight decrease in healthcare workers. CONCLUSIONS: Fragrance allergy is a significant problem in an occupational setting. Although there was no significant change in the incidence of fragrance-related allergic occupational contact dermatitis (OCD) during the 20-year study period, this does not mirror the trend in OCD, which is falling. Fragrance allergy continues to be a major contributor to OCD, and contributes to a greater proportion of cases.