Document Detail

Evaluation of a vision-related utility instrument: the German vision and quality of life index.
MedLine Citation:
PMID:  23341011     Owner:  NLM     Status:  MEDLINE    
PURPOSE: Multi-attribute utility instruments (MAUIs), which contain a descriptive system, including several health dimensions with associated levels of increasing severity, are used commonly to measure utilities. However, the validity of the descriptive systems rarely is examined using modern psychometric theory. Therefore, we evaluated the psychometric properties of the German version of the Vision and Quality of Life Index (VisQol), a six-item vision-related MAUI.
METHODS: The German VisQol was self-administered to 340 patients and 280 controls. All subjects underwent a full ophthalmologic examination, including best-corrected visual acuity (VA) testing. The psychometric properties of the VisQoL were assessed using Rasch analysis.
RESULTS: The VisQoL's descriptive system did not function in controls. In patients, after collapsing response categories to resolve disordered thresholds and omitting misfitting persons, the measurement properties (i.e., precision, unidimensionality, and targeting) of the German VisQoL were satisfactory. Most person misfit related to unexpected responses to item 4 ("organizing assistance"). Rasch-generated person estimates were not different between age categories, sex, or underlying ocular condition, but decreased significantly with presence of visual impairment in the better eye (LogMAR ≥ 0.5, 1.20 ± 4.62 compared to 3.46 ± 3.52, P < 0.001).
CONCLUSIONS: The German VisQoL's descriptive system displayed adequate fit to the Rasch model after removal of a large proportion of patients with poor fit statistics. However, the wording of item four should be revised to reduce respondent confusion and measurement "noise." The scale's descriptive system does not function in a sample of visually unimpaired persons, most likely due to a lack of variance in the measured trait.
Robert P Finger; Karsten Kortuem; Eva Fenwick; Bettina von Livonius; Jill E Keeffe; Christoph W Hirneiss
Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't; Validation Studies     Date:  2013-02-01
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  54     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2013 Feb 
Date Detail:
Created Date:  2013-02-14     Completed Date:  2013-04-09     Revised Date:  2013-08-08    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1289-94     Citation Subset:  IM    
Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia.
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MeSH Terms
Intraocular Pressure
Middle Aged
Outpatients / psychology
Psychometrics / methods*,  standards*
Quality of Life*
Questionnaires / standards
Reproducibility of Results
Vision Disorders / physiopathology*,  psychology*
Visual Acuity / physiology*
Visual Field Tests

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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