Brach Jennifer S, Studenski Stephanie A, Perera Subashan, VanSwearingen Jessie M, Newman Anne B
Department of Physical Therapy, University of Pittsburgh, Division of Geriatric Medicine, Department of Epidemiology, Pittsburgh, PA 15260, USA.
J Gerontol A Biol Sci Med Sci. 2007 Sep;62(9):983-8. doi: 10.1093/gerona/62.9.983.
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.
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.
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).
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.
步速是预测行走功能障碍发生的有力指标。本研究旨在确定步态变异性是否能独立于步速，增加对行动功能障碍发生的预测能力。
研究对象包括匹兹堡心血管健康研究中379名老年人（平均年龄79岁；78%为白种人，40%为男性）。所有参与者均能独立行走，且表示行走半英里无困难。步态特征通过4米长的计算机化步道测定。对于每个步态参数，变异性定义为两次行走过程中各步的标准差。通过每6个月进行一次为期54个月的电话访谈获取行走功能障碍的发生情况，行走功能障碍定义为行走半英里出现新的困难或无法行走半英里。
379名参与者中，222人（58.6%）出现了行动功能障碍。在未调整的Cox比例风险模型中，步速、平均步长、平均站立时间和站立时间变异性与行动功能障碍的发生相关。在调整了步速、人口统计学特征、慢性病、处方药、健康状况和身体活动水平后，只有站立时间变异性仍然是功能障碍的重要指标。在调整后的模型中，站立时间变异性每增加0.01秒，行动功能障碍的发生率就会增加13%（风险比1.13，95%置信区间1.01 - 1.27）。
站立时间变异性是未来行动功能障碍的独立预测指标。未来需要努力确定减少站立时间变异性的干预措施是否也能延缓行动功能障碍的发生。
