Abstract
Purpose: :
To develop standardized, vision-specific health states characterizing the functional impacts of NV-AMD according to logMAR (Early Treatment of Diabetic Retinopathy Study [ETDRS]) visual acuity and contrast sensitivity, and to elicit patient preference values for these health states.
Methods: :
Health state descriptions were developed through analysis of National Eye Institute Visual Functioning Questionnaire (VFQ) data, patient interviews, and physician feedback. Health state content was based on VFQ item wording and reflected key functional impacts experienced by patients with NV-AMD. Health states, anchored by perfect vision and death, were valued using the time-trade off method by a sample of 60 patients with ophthalmologist-diagnosed NV-AMD from two centres in Canada.
Results: :
The classification system assigns patients to a health state based on VA, difference in VA or CS between eyes, ability to drive, and ability to move about outside. Health state preference values for the 14 NV-AMD-specific health states were elicited from patients; the mean age was 78.6 years, and 40 (66.7%) were female. Mean preferences decreased from 0.99 (for best-eye logMAR <0.1 (Snellen equivalent acuity >20/25), worst-eye logMAR <1.0 (Snellen equivalent visual acuity >20/200), to 0.67 (for best eye logMAR >1.3 (Snellen equivalent visual acuity <20/400) or contrast sensitivity <21 letters bilaterally). Preferences decreased with increasing severity of functional deficits, and did not vary significantly by gender, age, or best- or worst-eye acuity.
Conclusions: :
The use of standardized vision-specific health states that incorporate logMAR visual acuity, contrast sensitivity, the better- and worse-seeing eye, and vision functioning make this study in NV-AMD unique. We demonstrated that increasing vision impairment as measured by these multiple factors is associated with a substantial decline in patient preference values.
Keywords: quality of life • age-related macular degeneration • clinical (human) or epidemiologic studies: health care delivery/economics/manpower