Accepted for/Published in: JMIR mHealth and uHealth
Date Submitted: Jul 22, 2020
Date Accepted: Apr 8, 2021
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
App-based versus standard 6MWT in pulmonary hypertension: pilot study
ABSTRACT
Background:
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 six-minute walk test (6MWT) in clinics. We developed a smartphone app to compute the walked distance (6MWD) indoor, by counting U-turns, and outdoor, by using satellite positioning.
Objective:
To assess a) accuracy of the indoor 6MWT in clinical settings, b) validity and test-retest reliability of outdoor 6MWT in the community, c) compliance, usability and acceptance of the app and d) feasibility of pulse oximetry during 6MWT.
Methods:
We tested the app on 30 PAH patients over 6 months. Patients were asked to perform 3 conventional 6MWT in clinic while using the app in the indoor mode and to perform one or more app-based 6MWT in outdoor mode in the community per month.
Results:
Bland-Altman analysis of 70 pairs of conventional vs app-based indoor 6MWD suggests that the app is seldom inaccurate (14.6 m mean difference, lower and upper limit of agreement: -133.35 m, 162.55 m). The comparison of 69 pairs of conventional 6MWD and community-based outdoor 6MWD within 7 days shows that community tests are strongly related to those performed in clinic (correlation: 0.89, standard error of measurement: 33.03 m). Analysis of 89 pairs of outdoor tests performed by the same patient within 7 days shows that community-based tests are repeatable (intraclass correlation 0.93, standard error of measurement: 26.03 m). Questionnaires and semistructured interviews indicate that the app is usable and well-accepted, but motivation to use it could be affected if the data is 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.
Conclusions:
App-based outdoor 6MWT in community settings is valid, repeatable and well accepted by patients. More studies would be needed to assess the benefits of using the app in clinical practice.
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