title: Inter-rater concordance study of the PASI (Psoriasis Area and Severity Index).
abstract: BACKGROUND
  Developed in 1978, the PASI (Psoriasis Area and Severity Index) is a method to rate psoriasis severity. Since then, it has been criticized for being extremely long, complex and for yielding significantly divergent interpretations.
  
  
  OBJECTIVE
  To determine the PASI inter-rater reliability among three independent evaluators examining the same patients.
  
  
  METHODS
  Cross-sectional study conducted in 2007 at a psoriasis treatment center, where 20 patients were selected. The patients were evaluated by three postgraduate students of Dermatology who independently determined the PASI of each patient. The inter-rater reliability coefficient was determined by employing intraclass correlation coefficients (ICC) and Bland & Altman plots.
  
  
  RESULTS
  An ICC of 0.729 (IC 95%: 0.440 - 0.882) showed a significant degree of concordance among evaluators. By graphic means, the Bland & Altman plot method presents concordance gap ranges. As shown in this study, narrow gap ranges indicate a good concordance degree. It was also observed that for high PASI values, wider concordance gap ranges predominate.
  
  
  CONCLUSIONS
  Based on this analysis, we may conclude that the PASI is a reliable indicator of psoriasis severity because it shows significant concordance when independent evaluations are performed.
authors.affiliation: Instituto de Dermatologia Prof. Rubem David Azulay, Santa Casa de Misericórdia do Rio de Janeiro, RJ, Brasil. joanarcf@gmail.com
authors.forename: Joana Ribeiro Costa de
authors.initials: JR
authors.lastname: Faria
authors.forename: Aline Rezende
authors.initials: AR
authors.lastname: Aarão
authors.forename: Luiz Miguel Zabaleta
authors.initials: LM
authors.lastname: Jimenez
authors.forename: Oscar Hernández
authors.initials: OH
authors.lastname: Silva
authors.forename: João Carlos Regazzi
authors.initials: JC
authors.lastname: Avelleira
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D006801:Humans; D008875:Middle Aged; D015588:Observer Variation; D011565:Psoriasis / Q000473:pathology*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D055815:Young Adult