Supplementary Material for: Monitoring gait and physical activity of elderly frail individuals in free-living environment: a feasibility study

Introduction: Frailty is conventionally diagnosed using clinical tests and self-reported assessments. However, digital health technologies (DHTs), such as wearable accelerometers, can capture physical activity and gait during daily life, enabling more objective assessments. In this study, we assess the feasibility of deploying DHTs in community-dwelling older individuals, and investigate the relationship between digital measurements of physical activity and gait in naturalistic environments and participants’ frailty status, as measured by conventional assessments. Methods: Fried Frailty Score (FFS) was used to classify fifty healthy individuals as non-frail (FFS=0, n/female=21/11, mean±sd age:71.10±3.59 years), pre-frail (FFS=1-2, n/female=23/9, age:73.74±5.52 years), or frail (FFS=3+, n/female=6/6, age:70.70±6.53 years). Participants wore wrist-worn and lumbar-worn GENEActiv accelerometers (Activinsights Ltd., Kimbolton, UK) during three in-lab visits, and at-home for 2 weeks, to measure physical activity and gait. After this period, they completed a comfort and usability questionnaire. Compliant days at-home were defined as follows: those with ≥18 hours of wear time, for the wrist-worn accelerometer, and those with ≥1 detected walking bout, for the lumbar-worn accelerometer. For each at-home measurement, a group analysis was performed using a linear regression model followed by ANOVA, to investigate the effect of frailty on physical activity and gait. Correlation between at-home digital measurements and conventional in-lab assessments was also investigated. Results: Participants were highly compliant in wearing the accelerometers, as 94% indicated willingness to wear the wrist device, and 66% the lumbar device, for at least 1 week. Time spent in sedentary activity and time spent in moderate activity as measured from the wrist device, as well as average gait speed and its 95th percentile from the lumbar device were significantly different between frailty groups. Moderate correlations between digital measurements and self-reported physical activity were found. Conclusions: This work highlights the feasibility of deploying DHTs in studies involving older individuals. The potential of digital measurements in distinguishing frailty phenotypes, while unobtrusively collecting unbiased data, thus minimizing participants’ travels to sites, will be further assessed in a follow-up study.

引言：衰弱综合征传统上通过临床检查与自我报告评估进行诊断。然而，数字健康技术（DHTs），如可穿戴加速度计，可捕捉日常生活中的身体活动与步态，从而实现更客观的评估。本研究旨在评估在社区居住老年人中应用DHTs的可行性，并探究自然场景下身体活动与步态的数字化测量结果与参与者的衰弱状态（通过传统评估方法测定）之间的关联。
方法：本研究采用弗里德衰弱评分（FFS）将50名健康受试者分为非衰弱组（FFS=0，男性/女性人数为11/21，平均年龄±标准差：71.10±3.59岁）、衰弱前期组（FFS=1~2，男性/女性人数为9/23，平均年龄±标准差：73.74±5.52岁）以及衰弱组（FFS≥3，男性/女性人数为6/6，平均年龄±标准差：70.70±6.53岁）。受试者在3次实验室访视期间以及居家2周期间佩戴腕部与腰部佩戴的GENEActiv加速度计（英国金博尔顿市Activinsights有限公司出品），以采集身体活动与步态数据。采集结束后，受试者完成一份舒适度与可用性问卷。居家有效佩戴天数定义如下：腕部加速度计的佩戴时长≥18小时，腰部加速度计检测到≥1次步行片段。针对每一项居家测量结果，本研究采用线性回归模型结合方差分析进行组间分析，以探究衰弱状态对身体活动与步态的影响；同时探究居家数字化测量结果与实验室传统评估结果之间的相关性。
结果：受试者对加速度计的佩戴依从性较高，94%的受试者表示愿意佩戴腕部设备，66%的受试者愿意佩戴腰部设备至少1周。腕部设备采集的久坐活动时长、中等强度活动时长，以及腰部设备采集的平均步态速度及其95百分位数，在不同衰弱组间均存在显著差异。数字化测量结果与自我报告的身体活动之间存在中等程度的相关性。
结论：本研究证实了在老年人相关研究中应用DHTs的可行性。数字化测量在区分衰弱表型方面具有潜力，同时可无干扰地收集无偏数据，从而减少受试者往返实验室的行程。这一方向的潜力将在后续研究中进一步评估。