Rasch Analysis in the Development of a Simplified Version of the National Eye Institute Visual-Function Questionnaire-25 for Utility Estimation

Published In: Quality of Life Research, v. 21, no. 2, Mar. 2012, p. 323-334

Posted on RAND.org on March 01, 2012

by Jonathan W Kowalski, Anne M Rentz, John G Walt, Andrew Lloyd, Jeff Lee, Tracey Young, Wen-Chen Chen, Neil M Bressler, Paul Lee, John E Brazier, Ron D. Hays, Dennis A. Revicki

Read More

Access further information on this document at Springer

This article was published outside of RAND. The full text of the article can be found at the link above.

PURPOSE: Preference-based health measures value how people feel about the desirability of a health state. Generic measures may not effectively capture the impact of vision loss from ocular diseases. Disease-targeted measures could address this limitation. This study developed a vision-targeted health state classification system based on the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25). METHODS: Secondary analysis of NEI VFQ-25 data from studies of patients with central (n = 932) - and peripheral-vision loss (n = 2,451) were used to develop a health state classification system. Classical test theory and Rasch analyses were used to identify a smaller set of NEI VFQ-25 items suitable for the central- and peripheral-vision-loss groups. RESULTS: Rasch analysis of the NEI VFQ-25 items using the peripheral vision–loss data indicated that 11 items fit a unidimensional model, while 14 NEI VFQ-25 items fit using the central-vision-loss data. Combining peripheral-vision-loss data and central-vision-loss data resulted in 9 items fitting a unidimensional model. Six items covering near vision, distance vision, social vision, role difficulties, vision dependency, and vision-related mental health were selected for the health-state classification. CONCLUSIONS: The derived health-state classification system covers relevant domains of vision-related functioning and well-being.

This report is part of the RAND Corporation external publication series. Many RAND studies are published in peer-reviewed scholarly journals, as chapters in commercial books, or as documents published by other organizations.

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.