School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
Translational and Clinical Research Unit, Clinical Ageing Research Unit, Newcastle University, Newcastle upon Tyne NE4 5PL, UK.
Sensors (Basel). 2020 May 5;20(9):2631. doi: 10.3390/s20092631.
Parkinson's disease (PD) is a common age-related neurodegenerative disease. Gait impairment is frequent in the later stages of PD contributing to reduced mobility and quality of life. Digital biomarkers such as gait velocity and step length are predictors of motor and cognitive decline in PD. Additional gait parameters may describe different aspects of gait and motor control in PD. Sample entropy (SampEnt), a measure of signal predictability, is a nonlinear approach that quantifies regularity of a signal. This study investigated SampEnt as a potential biomarker for PD and disease duration. Real-world gait data over a seven-day period were collected using an accelerometer (Axivity AX3, York, UK) placed on the low back and gait metrics extracted. SampEnt was determined for the stride time, with vector length and threshold parameters optimized. People with PD had higher stride time SampEnt compared to older adults, indicating reduced gait regularity. The range of SampEnt increased over 36 months for the PD group, although the mean value did not change. SampEnt was associated with dopaminergic medication dose but not with clinical motor scores. In conclusion, this pilot study indicates that SampEnt from real-world data may be a useful parameter reflecting clinical status although further research is needed involving larger populations.
帕金森病（PD）是一种常见的与年龄相关的神经退行性疾病。步态障碍在 PD 的后期很常见，导致活动能力和生活质量下降。步态速度和步长等数字生物标志物可预测 PD 患者的运动和认知能力下降。其他步态参数可描述 PD 患者不同的步态和运动控制方面。样本熵（SampEnt）是一种衡量信号可预测性的非线性方法，可量化信号的规律性。本研究探讨了 SampEnt 作为 PD 和疾病持续时间的潜在生物标志物。使用放置在腰部的加速度计（Axivity AX3，英国约克）采集了为期 7 天的真实世界步态数据，并提取了步态指标。确定了步长时间的 SampEnt，并优化了向量长度和阈值参数。与老年人相比，PD 患者的步长时间 SampEnt 更高，表明步态规律性降低。尽管平均值没有变化，但 PD 组的 SampEnt 范围在 36 个月内增加。SampEnt 与多巴胺能药物剂量相关，但与临床运动评分无关。总之，这项初步研究表明，来自真实世界数据的 SampEnt 可能是反映临床状况的有用参数，但需要进一步研究涉及更大的人群。
