title: Measurement properties of the Vitiligo Impact Scale-22 (VIS-22), a vitiligo-specific quality-of-life instrument.
abstract: BACKGROUND
  Vitiligo has a significant psychological impact which needs to be evaluated separately from the extent of depigmentation. We have developed a vitiligo-specific quality-of-life (QoL) instrument, Vitiligo Impact Scale-22 (VIS-22) for this purpose.
  
  
  OBJECTIVE
  To study the measurement properties of VIS-22 and compare it with the Dermatology Life Quality Index (DLQI) and Skindex-16.
  
  
  METHODS
  Item-reduction analysis was used to reduce the number of items in the original VIS from 27 to 22. The 5-point Physician's Global Assessment (PGA) was used to evaluate the QoL followed by a Visual Analogue Scale (VAS) to assess patient-perceived severity. VIS-22, DLQI and Skindex-16 were self-administered. The validity of the VIS-22 was assessed in 161 patients, reliability in 69 patients and responsiveness in 72 patients and compared with DLQI and Skindex-16.
  
  
  RESULTS
  Criterion validity was shown by strong correlation of VIS-22 with VAS (r = 0·7076). Convergent validity was evidenced by strong correlations with DLQI (r = 0·71) and Skindex-16 (r = 0·72). Known-groups validity was demonstrated by significantly higher scores in females, those with less education, patients with progressive disease and patients with vitiligo compared with controls (P < 0·001). Reliability was shown by excellent correlation of the scores between baseline and 2 weeks (r = 0·9053). VIS-22 was found to be responsive with scores at 12 weeks moving parallel to scores on VAS. Similar trends were noted with DLQI and Skindex-16.
  
  
  CONCLUSIONS
  VIS-22 is a valid, reliable and responsive QoL instrument. It is comparable to DLQI and Skindex-16 in its measurement properties, while being specific to the needs of patients with vitiligo.
authors.affiliation: Department of Dermatology and Venereology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India.
authors.forename: V
authors.initials: V
authors.lastname: Gupta
authors.forename: V
authors.initials: V
authors.lastname: Sreenivas
authors.forename: M
authors.initials: M
authors.lastname: Mehta
authors.forename: B K
authors.initials: BK
authors.lastname: Khaitan
authors.forename: M
authors.initials: M
authors.lastname: Ramam
mesh_terms: D000328:Adult; D001294:Attitude to Health; D016022:Case-Control Studies; D018450:Disease Progression; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires / Q000592:standards*; D014820:Vitiligo / Q000523:psychology*