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Sobha Sivaprasad, Rohit Varma, Neil M Bressler, David Silverman, Miriam Kimel, Elizabeth Tschosik, Chantal Dolan; Reliability and Construct Validity of National Eye Institute Visual Function Questionnaire-25 in Geographic Atrophy. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1980. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the reliability and construct validity of the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25) in patients with geographic atrophy (GA) secondary to age-related macular degeneration (AMD).
This was a post-hoc analysis of data from MAHALO, a randomized, sham-controlled, phase 1b/2 trial evaluating lampalizumab for GA secondary to AMD. The NEI VFQ-25 was administered to U.S. subjects (N=100) at baseline, 6, 12 and 18 months. Treatment arms were collapsed for this analysis. The NEI VFQ-25 was evaluated for reliability (internal consistency and test-retest) and validity (convergent and known-groups). Known-groups validity compared mean NEI VFQ-25 scores among clinically differentiated groups based on: GA lesion size; MNRead maximum reading speed, mean Functional Reading Independence Index (FRI Index) scores, and median best-corrected visual acuity. Results are presented for Composite, Near and Distance Activities subscales.
At baseline, Cronbach's alpha values for NEI VFQ-25 Composite, Near and Distance activities scores were 0.95, 0.84, and 0.84, respectively. Positive correlations were observed between the NEI VFQ-25 Composite, Near and Distance activities scores and the FRI Index (r=0.69, 0.73, and 0.64, respectively) and binocular reading speed (r=0.61, 0.69, and 0.57, respectively). Known groups validity at baseline was confirmed for groups defined by binocular measures: FRI index (F-values 40.4-56.7; all p<0.0001) and Reading Speed (F-values 21.3-47.6; all p<0.0001)], but not for monocular measures [GA lesion size, visual acuity (F-values 0.76-4.98; all p<0.05)]. Test-retest reliability was demonstrated in patients with relatively little GA lesion progression (<0.45mm2 growth, an estimate of inter-observer variability) between baseline and month 6: 0.86, 0.80 and 0.84, for Composite, Near and Distance Activities scales, respectively.
In MAHALO, NEI VFQ-25 Composite, Near and Distance Activities subscales showed good internal consistency reliability, test-retest reliability, convergent validity, and known-groups validity with binocular measures. These data support the use of the NEI VFQ-25 Composite, Near Activity and Distance Activity subscales as reliable and valid endpoints in clinical trials of GA secondary to AMD. The NEI VFQ-25 is being studied in the lampalizumab phase 3 studies in GA.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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