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Measurement properties of the Vitiligo Impact Scale‐22 ( VIS ‐22), a vitiligo‐specific quality‐of‐life instrument
Author(s) -
Gupta V.,
Sreenivas V.,
Mehta M.,
Khaitan B.K.,
Ramam M.
Publication year - 2014
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/bjd.13093
Subject(s) - vitiligo , dermatology life quality index , visual analogue scale , quality of life (healthcare) , medicine , depigmentation , dermatology , convergent validity , reliability (semiconductor) , correlation , clinical psychology , physical therapy , psychometrics , disease , internal consistency , quantum mechanics , power (physics) , physics , nursing , geometry , mathematics
Summary 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. Objectives 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.