Objective evaluation of skin prick test reactions using digital photography.
BACKGROUND
The skin prick test has been used worldwide to determine IgE-mediated hypersensitivity. However, the most current method to record this reaction has problems with accuracy and precision.


OBJECTIVE
To demonstrate a new approach to measure the skin prick reaction and its kinetics with precision.


METHODS
The skin prick test was induced using histamine or Dermatophagoides pteronyssinus antigen in 80 volunteers aged 4 and 67 years who had different skin colors. Digital photographs were obtained at 0, 3, 5, 10, 15 and 20 min. The mean wheal and erythema area as well as the erythema intensity were determined using Adobe Photoshop software. The accuracy and precision of this approach were also evaluated.


RESULTS
The digital photographic analysis measured the wheal and erythema sizes independent of the antigen or skin color with precision. In addition, a new variable of this test, the skin erythema intensity, could be determined objectively using the chromaticity of reflected light.


CONCLUSIONS
Digital photographic analysis is a precise and objective method to evaluate the skin prick test reaction, which can be used independent of the patient's skin color in clinical or research settings.
dos Santos
Rosaly Vieira
RV
Immunodermatology and Clinical Immunology Research Center at Federal University of Paraná, Paraná, Brazil.
Titus
Richard G
RG
Lima
Hermênio Cavalcante
HC
D000293:Adolescent; D000328:Adult; D000368:Aged; D039741:Antigens, Dermatophagoides; D002648:Child; D002675:Child, Preschool; D046169:Dermoscopy / Q000379:methods*; D004890:Erythema / Q000175:diagnosis*; D005260:Female; D006632:Histamine; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D012882:Skin Tests / Q000379:methods*
D039741:Antigens, Dermatophagoides; D006632:Histamine