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Visual function questionnaire detects clinically significant progression of AMD
The survey instrument was unresponsive to lens opacity progression, although color vision and driving scales were affected in some eyes.
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A widely used visual function questionnaire is capable of detecting clinically significant changes in vision in patients with age-related macular degeneration, a large multicenter study found.
The National Eye Institute Visual Function Questionnaire (NEI-VFQ) was administered to 4,119 participants as part of the multicenter Age-Related Eye Disease Study (AREDS). Each participant filled out the questionnaire, which consists of 25 items plus an appendix, at two visits separated by 1 to 4 years.
Changes in the NEI-VFQ overall and subscale scores of 10 points or more between test administrations were associated with clinically significant changes in vision and AMD, according to a study by Anne S. Lindblad, PhD, and colleagues with the Age-Related Eye Disease Study Group.
“This finding may assist the design of interventional studies of AMD and visual acuity loss that include the NEI-VFQ as an outcome measure,” the study authors said in describing their results in Archives of Ophthalmology.
Mean changes ranged from 11 to 25 points for the subscales of general vision, near and distance activities, social functioning, mental health, role difficulties, dependency, and driving, the authors said.
The questionnaire failed to detect meaningful change over time for lens opacity progression, although the authors said that when the event occurred in the eye with better vision at first administration, the lens opacity effect size was moderate for some subscales.
“Responsiveness refers to the ability of a measurement tool to detect meaningful change in populations over time and is also called ‘sensitivity to change,’” the authors said in their published paper. “In this report, we explore the responsiveness of the NEI-VFQ to documented progression in some of the primary outcomes used in AREDS, including advanced AMD, visual acuity loss and increased lens opacity. Our population provides the opportunity to assess the simultaneous effect of these outcomes on vision-targeted health-related quality of life.”
The median age of the population at the first administration of the questionnaire was 72 years (age range, 57-84 years). For more than half (59%) of the participants the second administration was 3 to 4 years after the first.
AMD progression
At enrollment in the AREDS, 24% of participants had no AMD (category 1), and 19% had advanced AMD in one eye (category 4). Responsiveness of the NEI-VFQ to progression to advanced AMD was assessed in 3,885 AREDS participants who had fundus photographs available for each administration.
Of those 3,885 participants, 364 demonstrated progression to advanced AMD in at least one eye between administrations. The investigators found that the overall score of the questionnaire was responsive (r = 14.0, P < .001) to progression to advanced AMD.
The subscales showing a moderate to large decrease in scores for progression to AMD included general vision (effect size = 0.67), near activities (0.76), distance activities (0.76), social functioning (0.84), mental health (0.54), role difficulties (0.67), dependency (0.83), and driving (0.85). The responsiveness statistic (RS) was equal to or exceeded 1 for the overall NEI-VFQ score (RS: 1.56) and for each of these subscales, with the exception of general vision (RS: 0.87) and mental health (0.92).
After adjusting for age, sex, race, AMD category and time between questionnaires, the mean difference in scores for participants with vs. those without progression to advanced AMD between the two questionnaire dates differed significantly for the overall NEI-VFQ and for all of the subscales, with the exception of general health and ocular pain. Significant differences ranged from eight points for general vision to slightly more than 19 points for driving.
Visual acuity
Progression to visual acuity loss was defined as a decrease of 15 or more letters in either eye. The responsiveness of the NEI-VFQ to progression of visual acuity loss was assessed in 3,624 AREDS participants with visual acuity of at least 20/200 in at least one eye at first administration.
Of the 3,624 participants, 485 demonstrated progression to VA loss in at least one eye between questionnaires. The overall score of the NEI-VFQ showed a moderate effect size and was highly responsive to VA loss, with an effect size of 0.74 and an RS of 1.76. The subscales of the NEI-VFQ that had moderate effect size and were also highly responsive to VA loss were general vision, distance activities, social functioning, role difficulties, dependency, and driving.
Visual acuity decrease was predominantly seen in subjects with progression to advanced AMD (68%). Only 19% of those with lens opacity progression experienced such loss.
After adjusting for age, sex, race, AMD category and time between questionnaires, the mean difference in scores for participants with vs. those without visual acuity loss between the two questionnaire dates differed significantly for the overall NEI-VFQ and for all subscales. The driving subscale had the largest difference, nearly 19 points.
The effect sizes for the overall score and all subscales were in the large range, except for general health, ocular pain, color vision, and peripheral vision.
“The mean differences in scores between administrations when visual acuity loss occurred in both eyes were at least twice the difference observed when visual acuity loss occurred in the eye with better vision,” the authors said.
Lens opacity
The questionnaire was unresponsive to progression to lens opacity (nuclear, cortical or posterior subcapsular), the study authors found. However, when the event occurred in the eye with the better vision at the first questionnaire session, the lens opacity effect size was moderate for the color vision and driving subsets. All other subscales, except ocular pain and peripheral vision, had small effect sizes, ranging from 0.22 to 0.47.
“It is possible that the lack of responsiveness to lens opacity in our study may have been influenced by the exclusion of persons who had cataract surgery,” the authors said. They also noted that their definition of opacity progression may have been too mild to elicit an impact on visual function at the start of follow-up in participants with no opacity or with mild opacity.
For Your Information:Reference:
- Anne S. Lindblad, PhD, and Traci E. Clemons, PhD, were the writing team for this study. Correspondence regarding the study can be addressed to the AREDS Coordinating Center, The Emmes Corporation, 401 N. Washington St., Suite 700, Rockville, MD 20850-1707; e-mail: aredspub@emmes.com.
- Age-Related Eye Disease Study Research Group. Responsiveness of the National Eye Institute Visual Function Questionnaire to progression to advanced age-related macular degeneration, vision loss, and lens opacity. AREDS Report No. 14. Arch Ophthalmol. 2005;123:1207-1214.
- Bob Kronemyer is an OSN Correspondent based in Elkhart, Ind.