title: The 5-point Investigator's Global Assessment (IGA) Scale: A modified tool for evaluating plaque psoriasis severity in clinical trials.
abstract: BACKGROUND
  To evaluate new psoriasis treatments, clinicians, regulators and pharmaceutical developers require well-accepted, clinically meaningful measures of disease severity. The Psoriasis Area and Severity Index (PASI) score is most widely used as a primary endpoint in clinical trials, although it is not routinely used in clinical practice.
  
  
  OBJECTIVE
  Characterize a 5-point Investigator's Global Assessment (IGA) tool and evaluate whether it meets the needs for a valid, clinically meaningful measure.
  
  
  METHODS
  A 5-point IGA tool was developed with input from regulatory authorities and clinical trial investigators involved with psoriasis drug development and evaluation. Associations between IGA 0/1 responder rates and PASI scores were evaluated using data from two phase 2 studies with the anti-interleukin (IL)-17A monoclonal antibody secukinumab (AIN457) that utilized a similar 6-point IGA.
  
  
  RESULTS
  The 5-point IGA has a more stringent definition for a score of 1 ("almost clear") compared with 6-point IGA/Physician's Global Assessment (PGA) tools used in previous trials of other biologics in moderate-to-severe psoriasis. Whereas IGA/PGA 0/1 responder rates for earlier scales are strongly associated with PASI 75, the IGA 0/1 rate for the secukinumab 6-point scale was more robust, demonstrating a strong association with PASI 90, and the results for the 5-point IGA are expected to show the same association.
  
  
  CONCLUSIONS
  The 5-point IGA is a valid measure of disease severity and meets the need for a clinically meaningful measure of success for psoriasis treatment studies.
authors.affiliation: Division of Dermatology, Department of Medicine, Queen Elizabeth II Health Sciences Centre, Dalhousie University , Halifax, Nova Scotia , Canada .
authors.forename: Richard G B
authors.initials: RG
authors.lastname: Langley
authors.forename: Steven R
authors.initials: SR
authors.lastname: Feldman
authors.forename: Judit
authors.initials: J
authors.lastname: Nyirady
authors.forename: Peter
authors.initials: P
authors.lastname: van de Kerkhof
authors.forename: Charis
authors.initials: C
authors.lastname: Papavassilis
mesh_terms: D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D001688:Biological Products / Q000627:therapeutic use; D006801:Humans; D011565:Psoriasis / Q000188:drug therapy* / Q000473:pathology; D012720:Severity of Illness Index
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D001688:Biological Products; C555450:secukinumab
keywords: IL-17; Investigator’s Global Assessment; Physician’s Global Assessment; Psoriasis Area and Severity Index; secukinumab