@article {987, title = {Gait variability and the risk of incident mobility disability in community-dwelling older adults.}, journal = {J Gerontol A Biol Sci Med Sci}, volume = {62}, year = {2007}, month = {2007 Sep}, pages = {983-8}, abstract = {

BACKGROUND: Gait speed is a strong predictor of incident walking disability. The objective was to determine if gait variability adds to the prediction of incident mobility disability independent of gait speed.

METHODS: Participants included 379 older adults (mean age = 79 years; 78\% Caucasian, and 40\% men) in the Cardiovascular Health Study at the Pittsburgh site. All could ambulate independently and reported no difficulty walking a half mile. Gait characteristics were determined from a 4-meter computerized walkway. For each gait parameter, variability was defined as the standard deviation from the individual steps from two passes. Incident walking disability was obtained by phone interview every 6 months for 54 months and was defined as new difficulty walking a half mile or inability to walk a half mile.

RESULTS: Of the 379 participants, 222 (58.6\%) developed incident mobility disability. In unadjusted Cox proportional hazards models gait speed, mean step length, mean stance time, and stance time variability were associated with incident mobility disability. After adjusting for gait speed, demographics, chronic conditions, prescription medications, health status, and physical activity level, only stance time variability remained an important indicator of disability. In the adjusted model, an increase in stance time variability of 0.01 seconds was associated with a 13\% higher incidence of mobility disability (hazard ratio 1.13, 95\% confidence interval, 1.01-1.27).

CONCLUSIONS: Stance time variability is an independent predictor of future mobility disability. Future efforts are needed to determine whether interventions that decrease stance time variability will also delay mobility disability.

}, keywords = {Aged, Aged, 80 and over, Aging, Cohort Studies, Female, Gait, Gait Disorders, Neurologic, Humans, Male, Mobility Limitation, Prospective Studies, Risk Factors, Walking}, issn = {1079-5006}, doi = {10.1093/gerona/62.9.983}, author = {Brach, Jennifer S and Studenski, Stephanie A and Perera, Subashan and VanSwearingen, Jessie M and Newman, Anne B} } @article {1024, title = {Incident physical disability in people with lower extremity peripheral arterial disease: the role of cardiovascular disease.}, journal = {J Am Geriatr Soc}, volume = {56}, year = {2008}, month = {2008 Jun}, pages = {1037-44}, abstract = {

OBJECTIVES: To evaluate the risk of incident physical disability and the decline in gait speed over a 6-year follow-up associated with a low ankle-arm index (AAI) in older adults.

DESIGN: Observational cohort study.

SETTING: Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Allegheny County, Pennsylvania.

PARTICIPANTS: Four thousand seven hundred five older adults, 58\% women and 17.6\% black, participating in the Cardiovascular Health Study.

MEASUREMENTS: AAI was measured in 1992/93 (baseline). Self-reported mobility, activity of daily living (ADL), and instrumental activity of daily living (IADL) disability and gait speed were recorded at baseline and at 1-year intervals over 6 years of follow-up. Mobility disability was defined as any difficulty walking half a mile and ADL and IADL disability was defined as any difficulty with 11 specific ADL and IADL tasks. Individuals with mobility, ADL, or IADL disability at baseline were excluded from the respective incident disability analyses.

RESULTS: Lower baseline AAI values were associated with increased risk of mobility disability and ADL/IADL disability. Clinical cardiovascular disease (CVD), diabetes mellitus, and interim CVD events partially explained these associations for mobility disability and clinical CVD and diabetes mellitus partially explained these associations for ADL and IADL disability. Individuals with an AAI less than 0.9 had on average a mean decrease in gait speed of 0.02 m/s per year, or a decline of 0.12 m/s over the 6-year follow-up. Prevalent CVD partly explained this decrease but interim CVD events did not further attenuate it.

CONCLUSION: Low AAI serves as marker of future disability risk. Reduction of disability risk in patients with a low AAI should consider cardiovascular comorbidity and the prevention of additional disabling CVD events.

}, keywords = {Activities of Daily Living, Aged, Cardiovascular Diseases, Cohort Studies, Comorbidity, Disability Evaluation, Female, Gait, Geriatric Assessment, Humans, Lower Extremity, Male, Mobility Limitation, Peripheral Vascular Diseases, Proportional Hazards Models, Risk Assessment, Risk Factors, United States}, issn = {1532-5415}, doi = {10.1111/j.1532-5415.2008.01719.x}, author = {Brach, Jennifer S and Solomon, Cam and Naydeck, Barbara L and Sutton-Tyrrell, Kim and Enright, Paul L and Jenny, Nancy Swords and Chaves, Paulo M and Newman, Anne B} }