title: Development and validation of a new clinically-meaningful rating scale for measuring lateral canthal line severity.
abstract: BACKGROUND
  Several scales have been employed for evaluating the effects of cosmetic treatments in the periorbital area. The Food and Drug Administration (FDA) has recently issued new recommendations specifying a rigorous process to validate new aesthetic scales.
  
  
  OBJECTIVE
  The authors describe and validate a new clinical rating scale: the Investigator's Global Assessment of Lateral Canthal Line (IGA-LCL) severity scale.
  
  
  METHODS
  The new FDA recommendations were utilized to validate the new scale. The first step was concept elicitation (based on direct input from clinicians, patients, and literature) and evaluation of content validity (appropriateness of concepts). The resulting five-point scale provided detailed descriptions of the lateral canthal lines (LCL), including quantitative assessment of LCL length and depth. Performance parameters, including intra- and interrater reproducibility and construct validity, were then evaluated in clinical studies. Finally, the scale's threshold for clinically-meaningful benefit and the ability of the scale to detect change were confirmed in two Phase 2b clinical studies involving a total of 270 subjects.
  
  
  RESULTS
  Content validity was established and the IGA-LCL scale showed excellent interrater reliability (weighted Kappa = 0.89) and interrater reliability (weighted Kappa = 0.77; Kendall's coefficient of concordance = 0.89). In clinical trials, the scale was sensitive enough to detect clinically-meaningful one- and two-point changes in LCL severity following treatment with topical botulinum toxin type A (BoNT-A). The authors observed statistically-significant correlations between the physician-rated IGA-LCL results and patient-reported outcomes.
  
  
  CONCLUSIONS
  The IGA-LCL scale was shown to be reliable, appropriate, and clinically meaningful for measuring LCL severity.
authors.affiliation: Manhattan Eye, Ear & Throat Institute, 115 East 67th Street, New York, NY 10065, USA. michaelkanemd@earthlink.net
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kane
authors.forename: Andrew
authors.initials: A
authors.lastname: Blitzer
authors.forename: Fredric S
authors.initials: FS
authors.lastname: Brandt
authors.forename: Richard G
authors.initials: RG
authors.lastname: Glogau
authors.forename: Gary D
authors.initials: GD
authors.lastname: Monheit
authors.forename: Rhoda S
authors.initials: RS
authors.lastname: Narins
authors.forename: Jean A
authors.initials: JA
authors.lastname: Paty
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Waugh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage*; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D015595:Skin Aging; D016896:Treatment Outcome; D014481:United States; D014486:United States Food and Drug Administration; D055815:Young Adult
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A