Community mobility among older adults with reduced kidney function: a study of life-space

Abstract

Background: Life-Space Assessment captures community mobility and social participation and quantifies the distance, frequency, and independence obtained as an older adult moves through his or her environment. Reduced estimated glomerular filtration rate (eGFR) is associated with decline in activities of daily living among older adults, but less is known about the association of eGFR with restrictions in mobility.

Study design: Prospective observational cohort study.

Setting & participants: Community-dwelling Medicare beneficiaries from the University of Alabama at Birmingham Study of Aging who had serum creatinine measured during a baseline in-home study visit and completed at least one telephone follow-up (N = 390).

Predictor: eGFR ≥ 60, 45-59, and <45 mL/min/1.73 m(2).

Outcome: Life-space mobility trajectory.

Measurements: Life-space mobility was evaluated by telephone every 6 months for up to 4.5 years using the previously validated Life-Space Assessment. Scores using this tool range from 0-120 (higher scores indicate greater mobility).

Results: Mean age of the 390 participants was 77.6 ± 5.8 (SD) years, 41% were African American, 50.5% were women; 30.0% had eGFR of 45-59 mL/min/1.73 m(2), and 20.2% had eGFR < 45 mL/min/1.73 m(2). Age-, race-, and sex-adjusted mean baseline life-space mobility scores were 64.8(95% CI, 62.0-67.6), 63.8 (95% CI, 60.3-67.4), and 58.3 (95% CI, 53.8-62.7) among those with eGFR categories ≥ 60, 45-59, and <45 mL/min/1.73 m(2), respectively. Compared with those with eGFRs ≥ 60 mL/min/1.73 m(2), a more rapid decline in life-space mobility was found among those with eGFRs < 45 mL/min/1.73 m(2), though this did not reach statistical significance (P=0.06); a similar effect was not seen among those with eGFRs of 45-59 mL/min/1.73 m(2) (P=0.3).

Limitations: Urinary albumin or longitudinal measures of eGFR were not available.

Conclusions: eGFR < 45 mL/min/1.73 m(2) was associated with a trend toward a more rapid decline in life-space mobility among community-dwelling older adults. Findings should be confirmed in a larger population.

Keywords: Chronic kidney disease; elderly; life-space mobility.

Figure 1

Conceptual model showing life-space levels with mean ± standard deviation for composite life-space score among all UAB Study of Aging participants (n=1000) by level achieved without help from another person in the four weeks before the baseline assessments completed between 1999-2001.

Figure 2

Logarithmic trajectory of life-space change by estimated glomerular filtration rate (eGFR) category. Adjusted for age, race, sex, rural residence, marital status, transportation difficulty, current smoking, less than high school education, diabetes, hypertension, stroke, peripheral vascular disease, obesity, coronary artery disease, hemoglobin level, Mini-Mental State Examination score, and Geriatric Depression Scale score.