title: Comparison between visual score and erythema index (DermaSpectrometer) in evaluation of allergic patch tests.
abstract: OBJECTIVE
  During the last decade several new bioengineering methods have been proposed for evaluation of patch test reactions in a more objective manner. The aim of the present study was to investigate the usefulness of erythema index (DermaSpectrometer) in a clinical setting, i.e., reading of allergic patch tests.
  
  
  METHODS
  Twenty patients with known allergy to formaldehyde participated in the study. Each patient had patch tests for 2 days with formaldehyde solutions from 0 to 10,000 p.p.m. applied. Clinical reading of the test sites and measurement of the erythema index by the DermaSpectrometer were done 24 h after removal. A control group of 20 volunteers with no allergy to formaldehyde were tested in a similar way.
  
  
  RESULTS
  Erythema indices were significantly higher for visually rated positive patch tests than for negative tests (P<0.05). The single categories of visually positive reactions (+?, +, ++, +++) could not be unambiguously separated by the DermaSpectrometer. The correlation between clinical readings and the formaldehyde concentration (Spearman's rank correlation coefficient, r=0.60) was higher than between DermaSpectrometer readings and the formaldehyde concentration (r=0.35).
  
  
  CONCLUSIONS
  In a dilution series of formaldehyde patch testing, readings from a DermaSpectrometer were not found to give better information than visual readings.
authors.affiliation: Department of Dermatology, University of Copenhagen, Gentofte HospitalCopenhagen Wound Healing Center, University of Copenhagen, Bispebjerg Hospital, Copenhagen, Denmark.
authors.forename: E
authors.initials: E
authors.lastname: Held
authors.affiliation: Department of Dermatology, University of Copenhagen, Gentofte HospitalCopenhagen Wound Healing Center, University of Copenhagen, Bispebjerg Hospital, Copenhagen, Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Lorentzen
authors.affiliation: Department of Dermatology, University of Copenhagen, Gentofte HospitalCopenhagen Wound Healing Center, University of Copenhagen, Bispebjerg Hospital, Copenhagen, Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Agner
authors.affiliation: Department of Dermatology, University of Copenhagen, Gentofte HospitalCopenhagen Wound Healing Center, University of Copenhagen, Bispebjerg Hospital, Copenhagen, Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Menné
keywords: DermaSpectrometer; allergic patch test; bioengineering methods; visual reading