Incident Physical Disability in People with Lower Extremity Peripheral Arterial Disease: The Role of Cardiovascular Disease

Abstract

Conclusion: A low ankle-brachial index (ABI) serves as a marker of future disability risk. Summary: The authors point out that an association exists between peripheral arterial disease (PAD) and function in people with clinically diagnosed PAD. The stimulus for this study is that it is actually unknown whether nondisabled community-dwelling older adults with low ABIs are at risk for development of new disability. In this study the authors evaluated the risk of incident physical disability and declining gait speed during a 6-year follow-up and associated this with low ABI in older adults. This was an observational cohort study conducted in Forsyth County, North Carolina; Sacramento California, Washington County, Maryland; and Allegheny County, Pennsylvania. There were 4705 older adults (58% women) participating in this study through the Cardiovascular Health Study; of these, 7.6% were African American. The ABI was measured at a baseline examination in 1992 or 1993. Baseline self-reported mobility, activities of daily living (ADL), and instrumental ADL, disability, and gait speed were recorded at baseline and at subsequent 1-year intervals for 6 years of follow-up. Mobility disability was defined as difficulty of any sort in walking one-half mile. Disability with ADL was described as difficulty with any 11 prespecified tasks. Patients with mobility disabilities or disabilities involving ADL at baseline were excluded from respective incident disability analysis. Lower baseline ABI values were associated with increased risk of late incident mobility disability and ADL disability. Associations for mobility disability were partially explained by cardiovascular disease, diabetes mellitus, and interim cardiovascular disease events. New ADL disability was partially explained by diabetes mellitus. Subjects with an ABI <0.9 had an average mean decreasing gait speed of 0.02 m/s per year, a decline of 0.12 m/s during 6 years of follow-up. This was partly explained by prevalent cardiovascular disease, but interim cardiovascular events did not contribute to this further. Comment: This study has some weaknesses in that disability in the subjects is based primarily on self-reporting. In addition, most of the patients in this study had mild peripheral arterial disease, and the results are likely not generalizable to patients with more severe decreases in their ABI. Nevertheless, it does appear that asymptomatic PAD, although well recognized as a risk for death from cardiovascular disease, is also a significant risk factor for future disability in asymptomatic patients.