Age-related cataract independently associated with frailty in elderly patients

Certain age-related cataracts may indicate a general functional decline in elderly patients independent of visual acuity and several other comorbidities, according to new findings from the Beaver Dam Eye Study.

Barbara E.K. Klein, MD, and colleagues at the University of Wisconsin-Madison School of Medicine and Public Health examined the relationship between three types of age-related cataracts and clinically defined frailty in 2,962 patients who were followed for 10 years.

Patients were assigned a frailty index score based on their gait time, peak expiratory flow rate, handgrip strength and their ability to stand from a sitting position.

"We found that each type of lens opacity was associated with at least one measure of frailty in men and women, after adjusting for age," the authors said. "In many analyses, relationships of cataract type to these [frailty] measures persisted after multivariable adjustment that included [visual acuity]," they added.

In the age-adjusted analysis, nuclear cataracts in women were associated with peak expiratory flow rate, handgrip strength and frailty index score. In addition, nuclear cataracts were associated with peak expiratory flow rate, gait time and frailty index score in men.

In multivariate analyses, nuclear cataracts were associated with both a slower gait time (P = .01) and a higher frailty index score (P = .01) in men, according to the study authors.

The multivariate analyses considered factors including age, visual acuity, pack-years of smoking, sedentary lifestyle, education and comorbidities, including cardiovascular disease, Alzheimer's, diabetes and hypertension.

Using multivariate analyses, the researchers found that cortical cataracts in women were associated with a lower peak expiratory flow rate (P < .01) and with weaker handgrip strength (P = .02) and a higher frailty index score (P < .01) in men.

Posterior subcapsular cataracts were also significantly associated with a lower peak expiratory flow rate (P = 0.01) in women in multivariable-adjusted models, but were not associated with any frailty measure in men, according to the study.

"Although this indicates the importance of adjusting for the other characteristics, it suggests that cataract status adds independently to at least some of the measures of frailty," the authors said. "A possible biologic mechanism responsible for our finding may be that because there are structural protein similarities in the lens and in skeletal tissues, there may be aging processes that affect both. In addition, unmeasured risk factors for cataract also may be risk factors for decline in the functions we measured," they said.

The study is published in the December issue of Ophthalmology.