title: Detection of Small Changes in Psoriasis Intensity with PrecisePASI.
abstract: BACKGROUND
  The Psoriasis Area and Severity Index (PASI) is the score of choice to grade psoriasis severity and detect clinical changes. Due to low resolution based on the calculation of the score by fixed area classes, PASI scores <10 have little value.
  
  
  METHODS
  At 756 patient examinations, psoriasis activity was measured with both PASI and PrecisePASI.
  
  
  RESULTS
  PrecisePASI has a linear increase while PASI has a staircase pattern. Both scores meet at the endpoint-relevant values of body surface area (BSA) 10, 30, 50, 70 and 90%. PASI and PrecisePASI correlate significantly over the whole range of BSA. In the region of BSA <5%, PrecisePASI shows a significantly higher resolution (p < 0.0001).
  
  
  CONCLUSIONS
  The calculation of PrecisePASI corrects the undesired inaccuracies of PASI in the lower BSA ranges and is a tool to use as an endpoint in trials aiming to detect differences in the lower ranges of BSA.
authors.affiliation: Department of Dermatology, University Hospital of Zurich, Zurich, Switzerland.
authors.forename: Antonios G A
authors.initials: AG
authors.lastname: Kolios
authors.forename: Lars E
authors.initials: LE
authors.lastname: French
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Navarini
mesh_terms: D000328:Adult; D000368:Aged; D001830:Body Surface Area; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000473:pathology*; D012720:Severity of Illness Index