title: A comparison between BSA, PASI, PLASI and SAPASI as measures of disease severity and improvement by therapy in patients with psoriasis.
abstract: BACKGROUND
  This study investigates four measures of disease severity in patients with psoriasis, both before and after therapy.
  
  
  METHODS
  Data records were analyzed from 33 patients with moderate-to-severe chronic plaque psoriasis who were treated with efalizumab, 1 mg/kg/week subcutaneously, for 12 weeks. Four measures of disease severity were used: body surface area (BSA), psoriasis area and severity index (PASI), psoriasis log-based area and severity index (PLASI) and self-administered PASI (SAPASI).
  
  
  RESULTS
  At the end of the 12-week therapy, the mean percent improvement shown by each measure varied considerably, ranging from 48.6% (PASI) to 70.6% (SAPASI). PASI and PLASI were the most comparable (67.3% and 66.5%). These differences were smaller when a dermatologist's opinion about the improvement was taken into account, for example "very good improvement" ranged from mean percent improvement of 63.8% (BSA) to 83.8% (PASI). The correlation between all measures revealed a high level of significance (P<or= 10(-5)).
  
  
  CONCLUSIONS
  Comparing the slopes and intercepts of the regression lines revealed PLASI as the most reliable measure for the severity and therapeutic improvement in patients with moderate-to-severe chronic plaque psoriasis. PLASI proved to be a marginally more accurate than PASI, and much more accurate than SAPASI and BSA. The superiority of PLASI may be a result of the logarithmic scale of the affected skin surface.
authors.affiliation: Department of Dermatology, University of Schleswig-Holstein, Kiel, Germany. Henseler@Dermatology.Uni-Kiel.de
authors.forename: Tilo
authors.initials: T
authors.lastname: Henseler
authors.forename: Karlheinz
authors.initials: K
authors.lastname: Schmitt-Rau
mesh_terms: D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D001830:Body Surface Area; D003879:Dermatologic Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000188:drug therapy*; D012044:Regression Analysis; D012720:Severity of Illness Index
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D003879:Dermatologic Agents; C472181:efalizumab