Adusumilli Gautam, Joseph Solomon Eben, Samaan Michael A, Schultz Brooke, Popovic Tijana, Souza Richard B, Majumdar Sharmila
Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Imaging, University of California San Francisco, San Francisco, CA, United States.
Human Performance Center, Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, CA, United States.
JMIR Mhealth Uhealth. 2017 Oct 27;5(10):e166. doi: 10.2196/mhealth.8656.
Performance tests are important to characterize patient disabilities and functional changes. The Osteoarthritis Research Society International and others recommend the 30-second Chair Stand Test and Stair Climb Test, among others, as core tests that capture two distinct types of disability during activities of daily living. However, these two tests are limited by current protocols of testing in clinics. There is a need for an alternative that allows remote testing of functional capabilities during these tests in the osteoarthritis patient population.
Objectives are to (1) develop an app for testing the functionality of an iPhone's accelerometer and gravity sensor and (2) conduct a pilot study objectively evaluating the criterion validity and test-retest reliability of outcome variables obtained from these sensors during the 30-second Chair Stand Test and Stair Climb Test.
An iOS app was developed with data collection capabilities from the built-in iPhone accelerometer and gravity sensor tools and linked to Google Firebase. A total of 24 subjects performed the 30-second Chair Stand Test with an iPhone accelerometer collecting data and an external rater manually counting sit-to-stand repetitions. A total of 21 subjects performed the Stair Climb Test with an iPhone gravity sensor turned on and an external rater timing the duration of the test on a stopwatch. App data from Firebase were converted into graphical data and exported into MATLAB for data filtering. Multiple iterations of a data processing algorithm were used to increase robustness and accuracy. MATLAB-generated outcome variables were compared to the manually determined outcome variables of each test. Pearson's correlation coefficients (PCCs), Bland-Altman plots, intraclass correlation coefficients (ICCs), standard errors of measurement, and repeatability coefficients were generated to evaluate criterion validity, agreement, and test-retest reliability of iPhone sensor data against gold-standard manual measurements.
App accelerometer data during the 30-second Chair Stand Test (PCC=.890) and gravity sensor data during the Stair Climb Test (PCC=.865) were highly correlated to gold-standard manual measurements. Greater than 95% of values on Bland-Altman plots comparing the manual data to the app data fell within the 95% limits of agreement. Strong intraclass correlation was found for trials of the 30-second Chair Stand Test (ICC=.968) and Stair Climb Test (ICC=.902). Standard errors of measurement for both tests were found to be within acceptable thresholds for MATLAB. Repeatability coefficients for the 30-second Chair Stand Test and Stair Climb Test were 0.629 and 1.20, respectively.
App-based performance testing of the 30-second Chair Stand Test and Stair Climb Test is valid and reliable, suggesting its applicability to future, larger-scale studies in the osteoarthritis patient population.
性能测试对于描述患者残疾情况和功能变化至关重要。国际骨关节炎研究学会及其他机构推荐30秒坐立试验和爬楼梯试验等作为核心测试，这些测试可捕捉日常生活活动中两种不同类型的残疾情况。然而，这两项测试受诊所现行测试方案的限制。需要一种替代方法，以便在骨关节炎患者群体的这些测试中对功能能力进行远程测试。
目标是（1）开发一款用于测试iPhone加速度计和重力传感器功能的应用程序，以及（2）开展一项试点研究，客观评估在30秒坐立试验和爬楼梯试验期间从这些传感器获得的结果变量的标准效度和重测信度。
开发了一款iOS应用程序，该程序具备从iPhone内置加速度计和重力传感器工具收集数据的能力，并与谷歌Firebase相连。共有24名受试者进行30秒坐立试验，试验过程中iPhone加速度计收集数据，外部评估者手动计数坐立重复次数。共有21名受试者进行爬楼梯试验，试验过程中打开iPhone重力传感器，外部评估者用秒表记录测试持续时间。来自Firebase的应用程序数据被转换为图形数据并导出到MATLAB中进行数据过滤。使用数据处理算法的多次迭代来提高稳健性和准确性。将MATLAB生成的结果变量与每项测试手动确定的结果变量进行比较。生成皮尔逊相关系数（PCC）、布兰德-奥特曼图、组内相关系数（ICC）、测量标准误差和重复性系数，以评估iPhone传感器数据相对于金标准手动测量的标准效度、一致性和重测信度。
30秒坐立试验期间应用程序加速度计数据（PCC = 0.890）和爬楼梯试验期间重力传感器数据（PCC = 0.865）与金标准手动测量高度相关。在将手动数据与应用程序数据进行比较的布兰德-奥特曼图上，超过95%的值落在95%一致性界限内。在30秒坐立试验（ICC = 0.968）和爬楼梯试验（ICC = 0.902）的试验中发现了很强的组内相关性。两项测试的测量标准误差均在MATLAB可接受的阈值范围内。30秒坐立试验和爬楼梯试验的重复性系数分别为0.629和1.20。
基于应用程序的30秒坐立试验和爬楼梯试验性能测试是有效且可靠的，表明其适用于未来针对骨关节炎患者群体的更大规模研究。
