The full scope of burden that glaucoma imposes on life satisfaction may be missed by general health-related utility rating instruments — and mental health aspects are not always addressed by current glaucoma-specific assessments. A newly developed Glaucoma Utility Instrument (Glau-U) aims to build on strengths of prior rating tools to gauge glaucoma-impacted quality of life (QoL), and analyze utilities, or cost-effectiveness of alternate treatments, according to an investigation published in JAMA Ophthalmology.
This cross-sectional study included patients at Singapore National Eye Centre glaucoma clinics diagnosed with mild, moderate, or advanced disease. Of 304 participants, 288 were applying topical medication, 67 received laser therapy, and 92 underwent glaucoma surgery. Stage 1 of the investigation comprised QoL attribute-finding and pretesting from June 2009 to May 2016, and stage 2 development and administration of the new system from May 2018 to December 2019. Glau-U uses an ordinal-type discrete choice experiment (DCE) survey; patients completed tasks rating how much or how often difficulty arose relating to 6 QoL attributes.
A survival attribute interacted with each of the life satisfaction attributes. The survival component focused on years lived — in increments of 5, 10, 15, or 20 years — at each state of health, from best possible glaucoma health state (0.92) to death (0). Year increments were based on stage 1 mean age of 67.5 years. Survival attribute-adjusted-impacts are:
- Activities of daily living; some difficulty (P =.02), severe difficulty (P <.001)
- Lighting and glare; some difficulty (P =.82), severe difficulty (P =.002)
- Movement; some difficulty (P <.001), severe difficulty (P <.001)
- Eye discomfort; sometimes (P =.90), often (P =.77)
- Other effects of glaucoma and its treatment; sometimes (P =.96), often (P =.14)
- Social and emotional effects; sometimes (P <.001), often (P <.001)
Quality-adjusted life-years (QALY) were calculated and rescaled for each health state. As glaucoma severity increased, difficulties also increased, with a drop “of up to 41% in quality-adjusted life-years compared with the best health state of preperimetric glaucoma.” Mean QALY weights lowered in relation to rise in severity of glaucoma in the better-seeing eye (P <.001). Thus, Glau-U demonstrated strong criterion validity.
A limitation of this study is the premise that the ocular health state may remain stable for 5 to 20 years. Investigators did not explore test-retest reliability. The population sample was based in 1 country only, and societal differences may apply to a DCE. A study strength is the widely varying disease intensities of participants — 95 experienced no glaucoma, 111 had mild disease, 60 displayed moderate glaucoma, 26 had severe disorder, and 12 were diagnosed with advanced or end-stage glaucoma in their better-seeing eye.
Health Technology Assessment protocols advise health economists to use a combination of general and condition-specific instruments. With Glau-U, best glaucoma health state values are converted to “perfect health” numbers for better matching the QALY scale of general instruments. “Glau-U could be useful in estimating the cost-effectiveness of alternative interventions for glaucoma and in informing the resource allocation policies for glaucoma and vision loss,” the analysis suggests.
Disclosures: Some of the study authors have declared affiliations with biotech and pharmaceutical companies. Please see the original reference for a full list of authors’ disclosures.
Fenwick EK, Ozdemir S, Man REK, et.al. Development and validation of a preference-based glaucoma utility instrument using discrete choice experiment. JAMA Ophthalmol. Published online June 24, 2021. doi:10.1001/jamaophthalmol.2021.1874