title: Condensation and validation of a 4-item index of the Acne-QoL.
abstract: BACKGROUND
  The 19-item Acne-QoL is a validated psychometric instrument designed for use in clinical trials.
  
  
  OBJECTIVE
  The purpose of this study was to develop a condensed version of the Acne-QoL as an alternative measure of psychosocial impact for use in routine clinical practice.
  
  
  METHODS
  Four condensed versions of the Acne-QoL were evaluated by regression analysis in a subset of 434 patients. The version with four items most broadly representative of acne-specific quality of life combined with a high level of correlation to Acne-QoL total score was selected for further validation in two different patient samples.
  
  
  RESULTS
  The patient ranked condensation, representing items from each domain of greatest patient-perceived importance and relevance was selected for further analysis (Acne-Q(4)). The Acne-Q(4) explained 98.5% of the variation in total score of Acne-QoL. Validation of the Acne-Q(4) in a follow-up group and an independent subset of patients resulted in Pearson correlation coefficients of 0.967 (p<0.001). Construct validity of the Acne-Q(4) was confirmed by demonstrating a similar relationship as the Acne-QoL to acne severity.
  
  
  CONCLUSIONS
  There is less breadth and detail of QoL information in the Acne-Q(4) than in the Acne-QoL. The analysis relied on a total score for Acne-QoL, which the original developers did not validate.
  
  
  CONCLUSIONS
  The Acne-Q(4) is accurately reflective of the parent instrument and may facilitate the psychometric evaluation of the impact of facial acne on patients in routine clinical practice by its practicality.
authors.affiliation: Department of Medicine, University of Western Ontario, London, ON, Canada.
authors.forename: Jerry
authors.initials: J
authors.lastname: Tan
authors.forename: Karen Y
authors.initials: KY
authors.lastname: Fung
authors.forename: Shahedul
authors.initials: S
authors.lastname: Khan
mesh_terms: D000152:Acne Vulgaris; D000293:Adolescent; D000328:Adult; D002170:Canada; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics; D011788:Quality of Life; D011795:Surveys and Questionnaires