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Sera Thomas, William G Hodge, Cindy M L Hutnik, Monali Malvankar; Utility Values associated with Ophthalmic Characteristics of Glaucoma and Diabetic Retinopathy (DR). Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2098. doi: https://doi.org/.
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Economic evaluations are essential to improving the efficiency of the healthcare system but require effect data called utility values which quantify Health-Related Quality of Life (HRQoL). This cross-sectional study (1) determines the relationship between utility values and ophthalmic characteristics such as OCT, IOP, and visual acuity and (2) determines a mathematical model that can convert clinical data into effect data.
The study was conducted at the Ivey Eye Institute at St. Joseph’s Hospital, Ontario. The study population included patients (n=50) with best-corrected visual acuity (BCVA) of 20/40 or worse in at least one eye and 80% of visual loss due to either glaucoma or DR. Standardized interviews and comprehensive ophthalmic examinations were performed. Medical and treatment history was recorded. The time-trade off method was applied to determine the HRQoL in units of utility values. Regression modelling was used to model the relationship between the ophthalmic characteristics and utility values.
The mean utility value for glaucoma patients was 0.94 + 0.15 and 0.81 + 0.33 for DR indicating good HRQoL compared to healthy individuals who have utility values of 1. Utility values increase and HRQoL improves as glaucoma patients either become older, have poorer vision, live longer with glaucoma, or have greater amounts of medical procedures for glaucoma. For each increase in BCVA, utility values decreased by 0.05 and for each additional medication taken there was a decrease by 0.06 (p<0.05). The model developed for DR suggested that lower utility values and poorer HRQoL were found in older ages, lower education levels, those who work, poorer vision in either eye, presence of ocular inflammation and/or ocular pain, and the greater amount of systemic medications. For each increase in BCVA, there was a decrease in utility value by 0.37 (p<0.05).
Ophthalmic characteristics of glaucoma and DR can be linked to utility values. Clinical variables, such as BCVA, presence of ocular inflammation or pain, and number of medications or comorbidities, demonstrated associations with utility values. This association is important to establish the role of clinical characteristics within an economic perspective. Current ophthalmic literature lacks utility values necessary to conduct accurate cost-effectiveness analysis and this study has provided this information.
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