App-Based Versus Standard Six-Minute Walk Test in Pulmonary Hypertension: Mixed Methods Study.

Dario Salvi,Elizabeth Orchard,Lionel Tarassenko,Emma Poffley

doi:10.2196/22748

Dario Salvi, Elizabeth Orchard + Show 2 more

Open Access

https://doi.org/10.2196/22748

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Abstract

BackgroundPulmonary 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.ObjectiveThe 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.MethodsWe 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.ResultsBland-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.ConclusionsApp-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.Trial RegistrationClinicalTrials.gov NCT04633538; https://clinicaltrials.gov/ct2/show/NCT04633538

Highlights

Pulmonary arterial hypertension (PAH) is a progressive illness that can be a severe life-limiting condition if not diagnosed early or left untreated [1]
The comparison of 69 pairs of conventional 6-minute walk test (6MWT) distance (6MWD) and community-based outdoor 6MWDs within 7 days shows that community tests are strongly related to those performed in clinic, but the interpretation of the distance should consider that differences above the clinically significant threshold are not uncommon
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

Summary

Introduction

Pulmonary arterial hypertension (PAH) is a progressive illness that can be a severe life-limiting condition if not diagnosed early or left untreated [1]. It is a chronic disease of the pulmonary vasculature, with vascular proliferation and remodeling of the small pulmonary arteries leading to a progressive increase in pulmonary vascular resistance. The 6-minute walk test (6MWT) is a standard method for measuring exercise capacity in patients with cardiopulmonary disease such as PAH. The 6MWT allows the patient to exercise at a daily functional level and is a useful tool for assessing severity of disease, and increasing walk distance correlates with a subjective improvement in dyspnea [5]. We developed a smartphone app to compute the walked distance (6MWD) indoors, by counting U-turns, and outdoors, by using satellite positioning

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