| Evaluation of a vision-related utility instrument - The German Vision and Quality of Life Index. | |
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MedLine Citation:
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PMID: 23341011 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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PURPOSE: Multi-attribute utility instruments (MAUIs) which contain a descriptive system including several health dimensions with associated levels of increasing severity are commonly used to measure utilities. However, the validity of the descriptive systems is rarely 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 ophthalmological 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 four ('organizing assistance'). Rasch generated person estimates were not different between age categories, gender 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 in order 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. |
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Authors:
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Robert P Finger; Karsten Kortuem; Eva Fenwick; Bettina von Livonius; Jill E Keeffe; Christoph W Hirneiss |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2013-1-22 |
Journal Detail:
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Title: Investigative ophthalmology & visual science Volume: - ISSN: 1552-5783 ISO Abbreviation: Invest. Ophthalmol. Vis. Sci. Publication Date: 2013 Jan |
Date Detail:
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Created Date: 2013-1-23 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7703701 Medline TA: Invest Ophthalmol Vis Sci Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Department of Ophthalmology, University of Bonn, Germany. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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