New Glaucoma Instrument Effectively Predicts Vision Impairment

A new glaucoma utility instrument (Glau-U) may be effective in estimating utilities across the spectrum of glaucoma severity, according to the results of a recent study.

To evaluate the effectiveness and validity of this preference-based instrument, the researchers conducted a cross-sectional study. The study was conducted in 2 stages and included 304 participants from the Singapore National Eye Centre glaucoma clinics. Participants included English- or Mandarin-speaking Singaporean citizens, or permanent residents of Chinese, Malay, or Indian ethnicity who were aged 40 years or older and had a clinical diagnosis of glaucoma in at least 1 eye.

The first stage, conducted between June 2009 and May 2016, identified and pretested the Glau-U attributes. The second stage, conducted between May 2018 and December 2019, developed and administered the discrete choice experiment (DCE) survey to participants. Activities of daily living, lighting and glare, movement, eye discomfort, other effects of glaucoma, and social and emotional effects were among the quality-of-life attributes that comprised the Glau-U.

Of the total participants, 92.4% (n = 281) had no vision impairment in the better eye, 4.3% (n = 13) had mild impairment, and 3.3% (n = 10) had moderate

to severe vision impairment. These results indicated that the mean Glau-U utilities decreased as better-eye glaucoma severity increased (none: 0.73 [0.21]; mild: 0.66 [0.21]; moderate: 0.66 [0.20]; severe: 0.60 [0.28]; advanced or end-stage: 0.22 [0.38]). When compared with a health state that included preperimetric glaucoma, there were reductions of 20.7% to 76.1% in quality-adjusted life-years.

Similarly, the mean Glau-U utilities decreased as better-eye vision impairment worsened (none: 0.67 [0.23]; mild 0.58 [0.32]; moderate to severe: 0.46 [0.29]).

Convergent and divergent validity was supported, as moderate correlations were observed between the Glau-U utilities and better-eye (r = 0.34) and worse-eye (r = 0.33) mean deviation scores. Low correlations were observed between Glau-U and EuroQol 5-Dimension utilities.

“These findings suggest that Glau-U is a valid glaucoma-specific utility instrument that can estimate utility weights that are associated with glaucoma and related vision impairment and can be used in cost-effectiveness analyses of interventions for glaucoma and vision loss,” the authors concluded.

—Leigh Precopio

Reference:

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. 10.1001/jamaophthalmol.2021.1874