One-legged stance sway of older adults with and without falls

Postural instability is a common problem among older people, and it is associated with mobility impairments, activity limitation and fear of falling. The evaluation of postural control can contribute to the early detection of balance deficits and help health professionals to manage this problem to prevent falls in older adults. The aim of this study was to identify center of pressure cut-offs to differentiate between older adults with and without falls in the past 12 months. The participants were 170 older adults (mean age 67 years, 50 fallers and 120 non-fallers). Center of pressure area and sway velocity in the anterior-posterior and medio-lateral directions were assessed using a force platform during three 30s one-legged stance trials with eyes open. The mean across trials was used for analysis. The time-limit (how long the participant was able to stay in one-legged stance, up to 30s) was also assessed. Fallers had poorer postural control than non-fallers (effect size ≥ 0.52, P 2 for Center of pressure area, 2.9 cm/s for velocity in the anterior-posterior, and 3.4 cm/s for medio-lateral velocity. The force platform parameters obtained an area under the curve of 0.72, with sensitivity of 78% and specificity of 68%. There were no significant differences between non-fallers and fallers for time-limit variable (17 seconds vs. 18 seconds). Force platform parameters during one-legged stance were associated with history of falls in older adults. The cut-offs obtained acceptable area under curve, sensitivity and specificity, with center of pressure area presenting the best performance to differentiate between fallers and non-fallers.姿势不稳是老年人常见的临床问题，常与运动功能障碍、活动受限及跌倒恐惧密切相关。姿势控制评估有助于早期识别平衡功能缺陷，可协助医护人员干预该问题，从而预防老年人跌倒。本研究旨在确定压力中心（Center of Pressure）截断值，以区分过去12个月内存在跌倒史与无跌倒史的老年人。本研究共纳入170名老年人（平均年龄67岁，其中50名有跌倒史，120名无跌倒史）。采用测力台（force platform）对受试者开展3次时长30秒的睁眼单腿站立测试，评估其前后方向与内外方向的压力中心面积及摆动速度，取各次测试的均值用于后续统计分析。同时还记录了单腿站立时长限制指标（即受试者可维持单腿站立的最长时长，上限为30秒）。有跌倒史者的姿势控制能力劣于无跌倒史者（效应量≥0.52，P 2），其中压力中心面积的截断值为2，前后方向摆动速度截断值为2.9 cm/s，内外方向摆动速度截断值为3.4 cm/s。测力台参数的曲线下面积（area under the curve）为0.72，灵敏度为78%，特异度为68%。单腿站立时长限制指标在两组间无显著差异（有跌倒史组为17秒，无跌倒史组为18秒）。单腿站立时的测力台参数与老年人跌倒史存在显著关联。所得截断值具备可接受的曲线下面积、灵敏度与特异度，其中压力中心面积在区分跌倒史者与无跌倒史者方面表现最优。