Daligadu Julian, Pollock Courtney L, Carlaw Kevin, Chin Morgan, Haynes Aspen, Thevaraajah Kopal Tharani, Tahsinul Anam, Walters Kaili, Colella Tracey J F
Rehabilitation Sciences Institute.
Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Vancouver.
Physiother Can. 2018 Fall;70(4):314-320. doi: 10.3138/ptc.2017-34.
This study examined the validity of the Fitbit Flex activity monitor for step count and distance walked among post-cardiac surgery patients. Participants (=20) from a major urban cardiac surgery centre were recruited 1-2 days before hospital discharge. The Fitbit Flex step count and distance walked outputs and video recording of each participant performing the 6-minute walk test were collected. Fitbit Flex output was compared with criterion measures of manual step count obtained from the video recording and manual measurement of distance walked. Statistical analysis compared the output and criterion measures using paired sample -tests, Pearson correlation coefficients, Lin's concordance correlations, and Bland-Altman plots. Sub-analysis compared slower walking (<0.8 m/s; =11) and faster walking (≥0.8 m/s; =8) group speeds (1 participant was excluded from analysis). Steps counted and distance walked were significantly different between the Fitbit Flex outputs and criterion measures (<0.05). The Fitbit Flex steps counted and distance walked showed moderate association with manual measure steps counted (=0.67) and distance walked (=0.45). Lin's concordance coefficients revealed a lack of agreement between the Fitbit Flex and the criterion measurement of both steps counted (concordance correlation coefficient [CCC]=0.43) and distance walked (CCC=0.36). The percentage of relative error was -18.6 (SD 22.7) for steps counted and 25.4 (SD 45.8) for distance walked. The Fitbit Flex activity monitor was not a valid measure of step count and distance walked in this sample of post-cardiac surgery patients. The lack of agreement between outputs and criterion measures suggests the Fitbit Flex alone would not be an acceptable clinical outcome measure for monitoring walking progression in the early postoperative period.
本研究检验了Fitbit Flex活动监测器在心脏手术后患者中步数计数和步行距离的有效性。从一个大型城市心脏手术中心招募了20名参与者，在出院前1 - 2天进行研究。收集了每位参与者进行6分钟步行测试时Fitbit Flex的步数计数和步行距离输出以及视频记录。将Fitbit Flex的输出与从视频记录中获得的手动步数计数和步行距离的标准测量值进行比较。统计分析使用配对样本t检验、Pearson相关系数、Lin一致性相关系数和Bland - Altman图比较了输出和标准测量值。亚组分析比较了较慢步行速度（<0.8米/秒；n = 11）和较快步行速度（≥0.8米/秒；n = 8）的组速度（1名参与者被排除在分析之外）。Fitbit Flex输出的步数计数和步行距离与标准测量值之间存在显著差异（P<0.05）。Fitbit Flex计数的步数和步行距离与手动测量的步数计数（r = 0.67）和步行距离（r = 0.45）显示出中等程度的相关性。Lin一致性系数显示Fitbit Flex与步数计数（一致性相关系数[CCC]=0.43）和步行距离（CCC = 0.36）的标准测量之间缺乏一致性。计数步数的相对误差百分比为-18.6（标准差22.7），步行距离的相对误差百分比为25.4（标准差45.8）。在这个心脏手术后患者样本中，Fitbit Flex活动监测器不是步数计数和步行距离的有效测量工具。输出与标准测量值之间缺乏一致性表明，仅使用Fitbit Flex作为监测术后早期步行进展的临床结局指标是不可接受的。
