Association of peripheral artery disease with life-space mobility restriction and mortality in community-dwelling older adults

Abstract

Objective: Symptomatic peripheral artery disease (PAD) impairs walking, but data on the impact of PAD on community mobility is limited. Life-space mobility measures the distance, frequency, and assistance needed as older adults move through geographic areas extending from their bedroom (life-space mobility score: 0) to beyond their town (life-space mobility score: 120). We evaluated the association of PAD with longitudinal life-space mobility trajectory.

Methods: Participants were part of the University of Alabama at Birmingham Study of Aging, a longitudinal study of community-dwelling older adults who were observed from 2001 to 2009. We limited our analysis to those who survived at least 6 months (N = 981). PAD was based on self-report with verification by physician report and hospital records. Our primary outcome was life-space mobility score assessed every 6 months. A multilevel change model (mixed model) was used to determine the association between PAD and life-space mobility trajectory during a median 7.9 years of follow-up.

Results: Participants had a mean age of 75.7 (standard deviation, 6.7) years; 50.5% were female, and 50.4% were African American. PAD prevalence was 10.1%, and 57.1% of participants with PAD died. In participants with both PAD and life-space restriction, defined as life-space mobility score <60, we observed the highest mortality (73.1%). In a multivariable adjusted mixed effects model, participants with PAD had a more rapid decline in life-space mobility by -1.1 (95% confidence interval [CI], -1.9 to -0.24) points per year compared with those without PAD. At 5-year follow-up, model-adjusted mean life-space mobility was 48.1 (95% CI, 43.5-52.7) and 52.4 (95% CI, 50.9-53.8) among those with and without PAD, respectively, corresponding to a restriction in independent life-space mobility at the level of one's neighborhood.

Conclusions: Life-space mobility is a novel patient-centered measure of community mobility, and PAD is associated with significant life-space mobility decline among community-dwelling older adults. Further study is needed to mechanistically confirm these findings and to determine whether better recognition and treatment of PAD alter the trajectory of life-space mobility.

Keywords: Life-space mobility; Mortality; Peripheral artery disease.

Figure I.

Conceptual model demonstrating the life-space mobility levels with mean +/− standard deviation for composite life-space score among all University of Alabama at Birmingham Study of Aging participants (N=1,000) by level reached independently in the 4 weeks before the baseline assessments completed in 1999–2001 (adapted from Bowling, et al.).

Figure II.. Mixed model trajectories for decline in life-space mobility score by peripheral artery disease (PAD) status.

The model was adjusted for all covariates including demographics, diabetes, hypertension, coronary artery disease, stroke, kidney disease, chronic obstructive pulmonary disease, congestive heart failure, gout/arthritis, and Geriatric Depression Scale score and Mini-Mental State Examination score. Participants with PAD had a more rapid decline in life-space mobility [(slope of - 1.09 points per year), (95% CI −1.9, −0.2); p-value = 0.01)] compared to those without PAD.

Figure III.. Kaplan-Meier curves showing survival curves for study subjects categorized in four different categories.

Categories were based on peripheral artery disease (PAD) and life-space mobility restriction (LSR) status, defined as life-space mobility score < 60). Subjects with both PAD and LSR showed a more rapid drop in survival probability compared to other categories.