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Characterization of Patients and Pattern of Sensitization at a New Mcmaster University Allergy and Dermatology Patch Test (ADPT) Clinic
Sunday, March 6, 2016
South Exhibit Hall H (Convention Center)
Sam Waserman, MD/MBA Candidate, Hermenio Lima, MD, PhD, David Fahmy, MD
Rationale: This is the first ADPT clinic in a tertiary care setting in Hamilton, Ontario. The epidemiology of contact allergen sensitization in this population is reported.

Methods: One hundred ninety seven adult patients referred to the ADPT Clinic from July 2014 to August 2015 underwent patch testing to 80 standardized reagents. A questionnaire on rash quality and potential exposures was administered. Reactions were graded as weak positive (erythematous papule with infiltration), strong (vesicle), or extreme (bulla), irritant or negative.

Results: Of 197 participants, median age was 49.2 years, and 70% were female. One hundred twenty two participants (62%) had at least one positive test, with a maximum of 6 positives (1%). Most prevalent positives were nickel sulphate hexahydrate (14%), fragrance mix I (8%) and cobalt chloride hexahydrate (8%). Neither gender nor age were statistically significant determinants of having one or multiple positives. Participants with nickel sulphate hexahydrate were mainly female and younger (P < 0.0112). Significant cross reactivity was noted between nickel sulphate hexahydrate, gold sodium thiosulphate dihydrate and potassium dichromate, as well as fragrance mix I, cinnamal, and myroxylon pereirae resin, and propylene glycol and dibucaine hydrochloride.

Conclusions: There is a significant demand for patch test services. Our findings are similar to those of other contact dermatitis studies in academic centres, thus supporting the clinical validity of the new ADPT clinic. An exceptional result was nickel, where positive patients were significantly younger than negatives.