title: A review of 241 subjects who were patch tested twice: could fragrance mix I cause active sensitization?
abstract: BACKGROUND
  Active patch test sensitization is an uncommon phenomenon which may have undesirable consequences for those undergoing this gold-standard investigation for contact allergy.
  
  
  OBJECTIVE
  To perform a retrospective analysis of the results of 241 subjects who were patch tested twice in a monocentre evaluating approximately 1500 subjects per year.
  
  
  METHODS
  Positivity to 11 common allergens in the recommended Baseline Series of contact allergens (European) was analysed: nickel sulphate; Myroxylon pereirae; fragrance mix I; para-phenylenediamine; colophonium; epoxy resin; neomycin; quaternium-15; thiuram mix; sesquiterpene lactone mix; and para-tert-butylphenol resin.
  
  
  RESULTS
  Only fragrance mix I gave a statistically significant, increased rate of positivity on the second reading compared with the first (P=0.011). This trend was maintained when separately analysing a subgroup of 42 subjects who had been repeat patch tested within 1 year; this analysis was done to minimize the potential confounding factor of increased usage of fragrances with a wide interval between both tests. To reduce the confounding effect of age on our data, we calculated expected frequencies of positivity to fragrance mix I based on previously published data from our centre. This showed a marked excess of observed cases over predicted ones, particularly in women in the age range 40-60 years.
  
  
  CONCLUSIONS
  We suspect that active sensitization to fragrance mix I may occur. Similar published analysis from another large group using standard methodology supports our data.
authors.affiliation: Department of Cutaneous Allergy, St John's Institute of Dermatology, St Thomas' Hospital, London SE1 7EH, UK. jonathanmlwhite@hotmail.com
authors.forename: J M L
authors.initials: JM
authors.lastname: White
authors.forename: J P
authors.initials: JP
authors.lastname: McFadden
authors.forename: I R
authors.initials: IR
authors.lastname: White
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003877:Dermatitis, Contact / Q000209:etiology*; D004853:Epoxy Resins / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029904:Myroxylon / Q000009:adverse effects*; D010328:Patch Tests / Q000009:adverse effects* / Q000706:statistics & numerical data; D010476:Perfume / Q000008:administration & dosage* / Q000009:adverse effects; D012107:Research Design; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D004853:Epoxy Resins; D010476:Perfume