Klein R, Moss SE, Klein BEK, Gutierrez P, Mangione CM. The NEI-VFQ-25 in people with long-term type 1 diabetes mellitus; the Wisconsin Epidemiology Study of Diabetic Retinopathy. Arch Ophthalmol 2001;119:733–740.
Original study reprint requests: Ronald Klein, Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, 610 North Walnut Street, 460 WARF, Madison, WI 53705–2397.
To examine the association of the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) overall and specific scale scores with visual acuity, diabetic retinopathy, and other characteristics, in a cohort of persons with type 1 diabetes.
A population-based cohort study.
Eleven counties in southern Wisconsin.
Supported by The National Institutes of Health, Bethesda, MD; and in part by the Senior Scientific Investigator Award from Research to Prevent Blindness Inc., New York, NY.
Univariate and multivariate analyses were used to evaluate the NEI-VFQ-25 score with multiple clinical parameters.
Visual acuity, the presence and severity of retinopathy and macular edema.
The total NEI-VFQ-25 score was lower in persons who were older, had a longer duration of diabetes, higher glycosylated hemoglobin, were in renal failure, had a history of cardiovascular disease, hypertension, or amputation of a lower limb, had poorer visual acuity, more severe diabetic retinopathy, macular edema, glaucoma, cataract, abnormality in tactile sensation or temperature sensitivity, smoked more total pack-years, led a more sedentary lifestyle, and had poor peak expiratory flow. While controlling for the physical and mental component scores from the Medical Outcomes Survey 36-Item Short-Form Health Survey as measures of comorbidity, lower total NEI-VFQ-25 scores were independently associated with poorer visual acuity, more severe retinopathy, older age, history of loss of tactile sensation, and more total pack-years of cigarettes smoked.
In this cross-sectional study, the 25-item NEI-VFQ seems to be strongly associated with vision, independent of severity of retinopathy and other complications associated with type 1 diabetes. It may be a useful measure of health-related quality of like as it relates to vision in epidemiology studies and clinical trials in persons with diabetes.
The article by Klein and coworkers makes a significant contribution to our understanding of factors that affect vision-related quality of life. They performed their measurement with the NEI-VFQ-25, a quality of life instrument developed under the auspices of the National Eye Institute. While there have been numerous reports on vision-related quality of life in patients with cataract from large populations, the application of quality of life measurement to patients with other eye disease such as age-related macular degeneration, optic neuritis, and glaucoma has largely been restricted to referral populations, with all of the attendant biases. Klein and coworkers break new ground by applying quality of life measurement methodology to a statewide, cross-sectional population of persons with diabetes.
As would be expected, the study shows a strong and linear correlation between visual acuity and vision-related quality of life (Fig. 2). As has been demonstrated in the case of cataract, visual acuity explained only 27.1% of the variance (R2) in VFQ-25 scores. This highlights the oft-replicated finding of Steinberg, et al. that Snellen visual acuity measurement captures only one dimension of the patient's perceived quality of vision and vision-related quality of life. 1
By virtue of their underlying disease, the diabetic persons in this study had higher levels of systemic illness and disability than those included in many previous vision-related quality of life studies. Univariate analyses revealed that the total NEI VFQ-25 score was lower in persons who were older, had a longer duration of diabetes, higher glycosylated hemoglobin, were in renal failure, had a history of cardiovascular disease, hypertension, or amputation of a lower limb, had more severe diabetic retinopathy, glaucoma, cataract, abnormal tactile sensation, or temperature sensitivity, smoked more total pack years, led a more sedentary lifestyle, and had poor peak expiratory flow. In attempting to determine which of these risk factors may be etiologic, it is important to recognize that many may be causes or evidence of advanced microvascular disease that is also associated with retinopathy and retinopathy-induced vision loss. The only vision-independent associations reported were for retinopathy level, age, loss of tactile sensation, and pack years of smoking. Each contributed to approximately 4 points on the 100 point VFQ scale across the entire range of its effect. Thus, in general, it seems that the effect of diabetic retinopathy in vision-related quality of life is largely related to the effect of retinopathy in Snellen Acuity. One unresolved issue that the authors might be able to elucidate is whether scatter laser photocoagulation has an effect on vision-related quality of life, independent of visual acuity.
1. Stein EP, Tielsch JM, Schein OD, et al. The VF-14: an index of functional impairment in patients with cataract. Arch Ophthalmol 1994; 112:630–638.