Sandroff Brian M, Motl Robert W, Pilutti Lara A, Learmonth Yvonne C, Ensari Ipek, Dlugonski Deirdre, Klaren Rachel E, Balantrapu Swathi, Riskin Barry J
Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Champaign, Illinois, United States of America.
PLoS One. 2014 Apr 8;9(4):e93511. doi: 10.1371/journal.pone.0093511. eCollection 2014.
There has been increased interest in the objective monitoring of free-living walking behavior using accelerometers in clinical research involving persons with multiple sclerosis (MS). The current investigation examined and compared the accuracy of the StepWatch activity monitor and ActiGraph model GT3X+ accelerometer for capturing steps taken during various speeds of prolonged, over-ground ambulation in persons with MS who had mild, moderate, and severe disability.
Sixty-three persons with MS underwent a neurological examination for generation of an EDSS score and undertook two trials of walking on the GAITRite electronic walkway. Participants were fitted with accelerometers, and undertook three modified six-minute walk (6MW) tests that were interspersed with 10-15 minutes of rest. The first 6MW was undertaken at a comfortable walking speed (CWS), and the two remaining 6MW tests were undertaken above (faster walking speed; FWS) or below (slower walking speed; SWS) the participant's CWS. The actual number of steps taken was counted through direct observation using hand-tally counters.
The StepWatch activity monitor (99.8%-99.9%) and ActiGraph model GT3X+ accelerometer (95.6%-97.4%) both demonstrated highly accurate measurement of steps taken under CWS and FWS conditions. The StepWatch had better accuracy (99.0%) than the ActiGraph (95.5%) in the overall sample under the SWS condition, and this was particularly apparent in those with severe disability (StepWatch: 95.7%; ActiGraph: 87.3%). The inaccuracy in measurement for the ActiGraph was associated with alterations of gait (e.g., slower gait velocity, shorter step length, wider base of support).
This research will help inform the choice of accelerometer to be adopted in clinical trials of MS wherein the monitoring of free-living walking behavior is of particular value.
在涉及多发性硬化症（MS）患者的临床研究中，使用加速度计对自由生活中的步行行为进行客观监测受到了越来越多的关注。本研究调查并比较了StepWatch活动监测仪和ActiGraph GT3X+加速度计在捕捉轻度、中度和重度残疾的MS患者在不同速度下长时间地面行走所走步数方面的准确性。
63名MS患者接受了神经学检查以生成扩展残疾状态量表（EDSS）评分，并在GAITRite电子步道上进行了两次步行试验。参与者佩戴加速度计，并进行了三次改良的六分钟步行（6MW）测试，测试之间穿插10 - 15分钟的休息时间。第一次6MW测试以舒适步行速度（CWS）进行，其余两次6MW测试分别以高于（较快步行速度；FWS）或低于（较慢步行速度；SWS）参与者的CWS进行。通过使用手动计数计数器直接观察来计算实际所走步数。
StepWatch活动监测仪（99.8% - 99.9%）和ActiGraph GT3X+加速度计（95.6% - 97.4%）在CWS和FWS条件下对所走步数的测量都显示出高度准确性。在SWS条件下，StepWatch在总体样本中的准确性（99.0%）优于ActiGraph（95.5%），这在重度残疾患者中尤为明显（StepWatch：95.7%；ActiGraph：87.3%）。ActiGraph测量的不准确与步态改变（如较慢的步态速度、较短的步长、更宽的支撑基底）有关。
本研究将有助于为MS临床试验中加速度计的选择提供参考，在这些试验中，对自由生活中的步行行为进行监测具有特别重要的价值。
