title: Erythema dose--a novel global objective index for facial erythema by computer-aided image analysis.
abstract: BACKGROUND
  Facial erythema is a common but morbid condition caused by several inflammatory disorders. Since most of the current severity indexes lack objectivity and global assessment, the computer-aided image analysis (CAIA) has been suggested.
  
  
  OBJECTIVE
  The purpose of this study is to compare the validity and efficacy of novel CAIA erythema index - erythema dose (ED) with two other CAIA indexes.
  
  
  METHODS
  For mild, moderated and severe erytherotelangiectatic rosacea patients, their photographs of right cheek were assessed with red-blue difference index in image (RBI), a*, and ED. For each index, the differences between severity groups were analyzed. The correlations between the three indexes were evaluated. To evaluate the capability of differentiating the pathologic erythema from the red component of the normal skin, each index was calculated at both the erythema and normal area.
  
  
  RESULTS
  The a* and ED significantly changed according to the severity, while the RBI did not. The ED was different between both mild-moderate and moderate-severe, while the a* only between mild-moderate. There was a strong positive correlation between a* and ED. The difference between erythema and normal skin was more prominent in ED than in a*.
  
  
  CONCLUSIONS
  We confirmed that the ED is well correlated with both subjective assessment, as well as the other CAIA index a*. The ED has the advantage of specifically visualizing and analyzing the pathologic erythema.
authors.affiliation: Department of Dermatology, Seoul National University, College of Medicine and Seoul National University, Bundang Hospital, Seongnam, Korea.
authors.forename: Jae Woo
authors.initials: JW
authors.lastname: Choi
authors.forename: Soon Hyo
authors.initials: SH
authors.lastname: Kwon
authors.forename: Seong Moon
authors.initials: SM
authors.lastname: Jo
authors.forename: Sang Woong
authors.initials: SW
authors.lastname: Youn
mesh_terms: D000328:Adult; D004890:Erythema / Q000145:classification* / Q000175:diagnosis*; D005148:Facial Dermatoses / Q000145:classification* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008875:Middle Aged; D010363:Pattern Recognition, Automated / Q000379:methods; D010781:Photography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
keywords: color deconvolution; computer-aided image analysis; facial erythema; objective assessment; rosacea