Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom.
Department of Cardiology, Oxford University National Health Service Foundation Trust, Oxford, United Kingdom.
JMIR Mhealth Uhealth. 2021 Jun 7;9(6):e22748. doi: 10.2196/22748.
Pulmonary arterial hypertension (PAH) is a chronic disease of the pulmonary vasculature that can lead to heart failure and premature death. Assessment of patients with PAH includes performing a 6-minute walk test (6MWT) in clinics. We developed a smartphone app to compute the walked distance (6MWD) indoors, by counting U-turns, and outdoors, by using satellite positioning.
The goal of the research was to assess (1) accuracy of the indoor 6MWTs in clinical settings, (2) validity and test-retest reliability of outdoor 6MWTs in the community, (3) compliance, usability, and acceptance of the app, and (4) feasibility of pulse oximetry during 6MWTs.
We tested the app on 30 PAH patients over 6 months. Patients were asked to perform 3 conventional 6MWTs in clinic while using the app in the indoor mode and one or more app-based 6MWTs in outdoor mode in the community per month.
Bland-Altman analysis of 70 pairs of conventional versus app-based indoor 6MWDs suggests that the app is sometimes inaccurate (14.6 m mean difference, lower and upper limit of agreement: -133.35 m to 162.55 m). The comparison of 69 pairs of conventional 6MWDs and community-based outdoor 6MWDs within 7 days shows that community tests are strongly related to those performed in clinic (correlation 0.89), but the interpretation of the distance should consider that differences above the clinically significant threshold are not uncommon. Analysis of 89 pairs of outdoor tests performed by the same patient within 7 days shows that community-based tests are repeatable (intraclass correlation 0.91, standard error of measurement 36.97 m, mean coefficient of variation 12.45%). Questionnaires and semistructured interviews indicate that the app is usable and well accepted, but motivation to use it could be affected if the data are not used for clinical decision, which may explain low compliance in 52% of our cohort. Analysis of pulse oximetry data indicates that conventional pulse oximeters are unreliable if used during a walk.
App-based outdoor 6MWTs in community settings are valid, repeatable, and well accepted by patients. More studies would be needed to assess the benefits of using the app in clinical practice.
ClinicalTrials.gov NCT04633538; https://clinicaltrials.gov/ct2/show/NCT04633538.
肺动脉高压（PAH）是一种慢性肺血管疾病，可导致心力衰竭和过早死亡。PAH 患者的评估包括在诊所进行 6 分钟步行测试（6MWT）。我们开发了一款智能手机应用程序，通过计算折返次数来计算室内的步行距离（6MWD），并通过卫星定位来计算室外的步行距离。
本研究旨在评估（1）临床环境中室内 6MWT 的准确性，（2）社区中室外 6MWT 的有效性和重测信度，（3）应用程序的依从性、可用性和可接受性，以及（4）6MWT 期间脉搏血氧饱和度的可行性。
我们在 6 个月内对 30 名 PAH 患者进行了测试。要求患者在诊所进行 3 次常规 6MWT，同时在室内模式下使用该应用程序，并在每月一次在社区中进行一次或多次基于应用程序的 6MWT。
70 对常规与基于应用程序的室内 6MWD 的 Bland-Altman 分析表明，该应用程序有时不准确（平均差值为 14.6m，一致性上下限为-133.35m 至 162.55m）。在 7 天内对 69 对常规 6MWD 和社区内室外 6MWD 的比较表明，社区测试与在诊所进行的测试密切相关（相关性 0.89），但对距离的解释应考虑到不常见的差异超过临床显著阈值。对同一患者在 7 天内进行的 89 次室外测试的分析表明，社区内的测试是可重复的（组内相关系数 0.91，测量误差 36.97m，平均变异系数 12.45%）。问卷调查和半结构化访谈表明，该应用程序具有可用性且易于接受，但如果数据不用于临床决策，可能会影响使用该应用程序的积极性，这可能解释了我们研究队列中 52%的患者依从性较低的原因。脉搏血氧饱和度数据分析表明，在行走过程中使用常规脉搏血氧仪不可靠。
社区环境中基于应用程序的室外 6MWT 是有效、可重复的，且患者易于接受。还需要更多的研究来评估在临床实践中使用该应用程序的益处。
ClinicalTrials.gov NCT04633538；https://clinicaltrials.gov/ct2/show/NCT04633538。
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