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Chris Cho, Aleksandra Mihailovic, Sheila K West, David S. Friedman, Laura N. Gitlin, Pradeep Y Ramulu; In-clinic vs. Free-living Ambulatory Cadence in Patients with Glaucoma. Invest. Ophthalmol. Vis. Sci. 2021;62(8):3528.
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© ARVO (1962-2015); The Authors (2016-present)
Visual impairment is a major risk factor for gait disturbances in glaucoma. Previously reported gait changes obtained in the laboratory setting may not accurately reflect one’s free-living ambulatory behavior. The objectives of this study were to: 1) compare lab-measured and real-world cadences in glaucoma patients, and 2) explore the relationship between each cadence metric with visual field (VF) damage.
Demographics and health data were acquired on 242 participants of the Falls in Glaucoma Study. Visual field testing results on each eye were combined into an integrated visual field (IVF) sensitivity to judge glaucoma severity. Cadence was defined as the average number of steps taken per minute. Lab-measured (gait mat) cadence was obtained using a GAITRite electronic walkway at the baseline clinical evaluation. Real-world cadence was estimated as the peak 1-min cadence using 7-day GPS and accelerometer data. Peak 1-min cadence was calculated as the highest cadence value for a single minute on each individual day, averaged over all valid days of the 7-day accelerometer trial. Average peak at-home and away from home cadences were calculated in the same fashion, with subject location determined by GPS data. Negative binomial regression models were used to determine the association between cadence metrics and VF damage.
Study participant characteristics are described in Table 1. Mean gait mat cadence was greater than the mean real-world cadence (107 vs. 91 steps/min; P<0.001), with intra-person gait mat and real-world cadences demonstrating only weak positive correlation (r=0.29; P<0.001). VF damage showed no association with gait mat cadence (RR=1.01; 95%CI, 0.99-1.02; P=0.50), but each 5-dB decrement in IVF was associated with a 6% slower real-world cadence (RR=0.94, 95%CI, 0.90-0.97; P=0.001) (Table 2). Associations of real-world cadence with IVF sensitivity persisted for both at-home (RR=0.94; 95%CI, 0.89-0.99; P=0.03) and away from home cadences (RR=0.96; 95%CI, 0.92-0.99; P=0.02) (Table 2).
Lab-measured cadence largely overestimates and poorly correlates with real-world cadence in patients with glaucoma. Greater VF damage was found to be associated with slower real-world cadence. Our findings indicate that gait metrics that are obtained in a controlled environment may not accurately reflect the free-living ambulatory behaviors of glaucoma patients.
This is a 2021 ARVO Annual Meeting abstract.
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