Data_Sheet_1_The Stepping Threshold Test for Reactive Balance: Validation of Two Observer-Based Evaluation Strategies to Assess Stepping Behavior in Fall-Prone Older Adults.zip

Introduction: Measurement of reactive balance is critical for fall prevention but is severely underrepresented in the clinical setting due to the lack of valid assessments. The Stepping Threshold Test (STT) is a newly developed instrumented test for reactive balance on a movable platform, however, it has not yet been validated for fall-prone older adults. Furthermore, different schemes of observer-based evaluation seem possible. The aim of this study was to investigate validity with respect to fall risk, interpretability, and feasibility of the STT using two different evaluation strategies.
Methods: This study involved 71 fall-prone older adults (aged ≥ 65) who underwent progressively increasing perturbations in four directions for the STT. Single and multiple-step thresholds for each perturbation direction were determined via two observer-based evaluation schemes, which are the 1) consideration of all steps (all-step-count evaluation, ACE) and 2) consideration of those steps that extend the base of support in the direction of perturbation (direction-sensitive evaluation, DSE). Established balance measures including global (Brief Balance Evaluations Systems Test, BriefBEST), proactive (Timed Up and Go, TUG), and static balance (8-level balance scale, 8LBS), as well as fear of falling (Short Falls Efficacy Scale—International, FES-I) and fall occurrence in the past year, served as reference measurements.
Results: The sum scores of STT correlated moderately with the BriefBEST (ACE: r = 0.413; DSE: r = 0.388) and TUG (ACE: r = −0.379; DSE: r = −0.435) and low with the 8LBS (ACE: r = 0.173; DSE: r = 0.246) and Short FES-I (ACE: r = −0.108; DSE: r = −0.104). The sum scores did not distinguish between fallers and non-fallers. No floor/ceiling effects occurred for the STT sum score, but these effects occurred for specific STT thresholds for both ACE (mean floor effect = 13.04%, SD = 19.35%; mean ceiling effect = 4.29%, SD = 7.75%) and DSE (mean floor effect = 7.86%, SD = 15.23%; mean ceiling effect = 21.07%, SD = 26.08). No severe adverse events occurred.
Discussion: Correlations between the STT and other balance tests were in the expected magnitude, indicating convergent validity. However, the STT could not distinguish between fallers and non-fallers, referring to a need for further studies and prospective surveys of falls to validate the STT. Current results did not allow a definitive judgment on the advantage of using ACE or DSE. Study results represented a step toward a reactive balance assessment application in a clinical setting.

引言：反应性平衡（reactive balance）的测量对跌倒预防至关重要，但由于缺乏有效评估工具，其在临床场景中的应用严重不足。踏步阈值测试（Stepping Threshold Test, STT）是一种新近开发的可移动平台反应性平衡仪器化评估工具，但尚未针对跌倒高风险老年人完成效度验证。此外，观察者导向的评估存在多种可行方案。本研究旨在探讨采用两种不同评估策略时，STT针对跌倒风险的有效性、可解释性及可行性。

方法：本研究纳入71名年龄≥65岁的跌倒高风险老年人，对其开展STT测试，施加四个方向的渐进式递增平台扰动。通过两种观察者评估方案确定各扰动方向的单步与多步阈值：1）纳入所有步数的计数评估（all-step-count evaluation, ACE）；2）纳入沿扰动方向扩展支撑面的步数的方向敏感评估（direction-sensitive evaluation, DSE）。以公认的平衡评估指标作为参照：包括整体平衡（简明平衡评估系统测试，Brief Balance Evaluations Systems Test, BriefBEST）、主动平衡（计时起身行走测试，Timed Up and Go, TUG）、静态平衡（8级平衡量表，8-level balance scale, 8LBS），以及跌倒恐惧（简明跌倒效能感量表-国际版，Short Falls Efficacy Scale—International, FES-I）和过去1年跌倒发生情况。

结果：STT总分与BriefBEST呈中度相关（ACE: r=0.413；DSE: r=0.388），与TUG呈中度负相关（ACE: r=-0.379；DSE: r=-0.435），与8LBS（ACE: r=0.173；DSE: r=0.246）及简明FES-I（ACE: r=-0.108；DSE: r=-0.104）呈低度相关。STT总分无法区分跌倒者与非跌倒者。STT总分未出现地板/天花板效应，但两种评估策略的特定STT阈值均存在该效应：ACE组平均地板效应为13.04%，标准差（SD）=19.35%，平均天花板效应为4.29%，SD=7.75%；DSE组平均地板效应为7.86%，SD=15.23%，平均天花板效应为21.07%，SD=26.08%。本研究未发生严重不良事件。

讨论：STT与其他平衡测试的相关性符合预期强度，提示其具有聚合效度。但STT无法区分跌倒者与非跌倒者，表明需开展进一步研究及跌倒前瞻性随访以验证STT的效度。目前的结果无法明确判定ACE或DSE的优势。本研究结果为反应性平衡评估应用于临床场景迈出了重要一步。