Prevalence of patch test results from 1970 to 2002 in a multi-centre population in North America (NACDG)

Contact Dermatitis. 2008 Feb;58(2):101-6. doi: 10.1111/j.1600-0536.2007.01281.x.


Background: The North American Contact Dermatitis Group (NACDG) has members who assess subjects with suspected allergic contact dermatitis (ACD) and patch tests them with the same screening allergens using a standardized procedure permitting analysis of long-term trends in patch test reactions.

Objective: This study reports the trends in prevalence patch test positivity of allergens by pooling data collected by the NACDG between 1970 and 2002.

Patients/methods: Patients were tested with the screening series of allergens, using a standardized technique. Data from these patients were recorded on a standard computer entry form and analysed. More than 100 allergens were tested on over 34,000 patients during several patch studies between the period. The Cochran-Armitage test of trend is used to evaluate changes in prevalence over time.

Results: 4 trends are noticed: (1) The incidence of presumed allergic nickel (P < 0.0001) and quaternium-15 (P < 0.0001) reactions rose with consistency over the years. (2) While that of cinnamic aldehyde (P = 0.21) and p-phenylenediamine (P < 0.0001) decreased. (3) The prevalence of positive reactions for potassium dichromate (P < 0.0001) shows an initial steady decrease but then a sharp increase starting from the 1996 period. (4) In contrast, thiuram (P = 0.0008) and neomycin (P < 0.0001) show an initial general increase, with a sharp decrease between 1998 and 2002.

Conclusion: Implications for opportunities to prevent ACD by utilizing less-allergenic alternatives appear robust; however, we do not wish to over generalize interpretations because of important limitations.

Publication types

  • Multicenter Study

MeSH terms

  • Acrolein / adverse effects
  • Acrolein / analogs & derivatives
  • Allergens / adverse effects*
  • Dermatitis, Allergic Contact / diagnosis
  • Dermatitis, Allergic Contact / epidemiology*
  • Dermatitis, Allergic Contact / etiology
  • Humans
  • Methenamine / adverse effects
  • Methenamine / analogs & derivatives
  • Neomycin / adverse effects
  • Nickel / adverse effects
  • North America / epidemiology
  • Patch Tests / trends*
  • Phenylenediamines / adverse effects
  • Potassium Dichromate / adverse effects
  • Prevalence
  • Thiram / adverse effects


  • Allergens
  • Phenylenediamines
  • Thiram
  • nickel sulfate
  • Acrolein
  • Nickel
  • quaternium-15
  • Neomycin
  • Methenamine
  • cinnamaldehyde
  • Potassium Dichromate
  • 4-phenylenediamine