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

Area of Science:

• Cardiology
• Pulmonary Medicine
• Digital Health

Background:

• Pulmonary arterial hypertension (PAH) is a severe vascular disease impacting the lungs and heart.
• The 6-minute walk test (6MWT) is crucial for assessing PAH patient functional capacity.
• A novel smartphone application was developed to measure 6-minute walk distance (6MWD) both indoors and outdoors.

Purpose of the Study:

• To evaluate the accuracy of the app's indoor 6MWT in clinical settings.
• To determine the validity, reliability, and patient acceptance of outdoor 6MWTs conducted in the community.
• To assess the feasibility of using pulse oximetry during 6MWTs.

Main Methods:

• 30 PAH patients participated over 6 months, performing in-clinic and community-based 6MWTs using the app.
• Indoor 6MWDs were compared to conventional tests using Bland-Altman analysis.
• Outdoor 6MWDs were assessed for validity against in-clinic tests and for test-retest reliability.

Main Results:

• The app's indoor 6MWD showed significant variability compared to conventional tests (mean difference 14.6 m).
• Outdoor community-based 6MWTs demonstrated strong correlation (0.89) and repeatability (ICC 0.91) with in-clinic tests.
• Patient acceptance was high, but app compliance was low (52%), potentially linked to clinical data integration.

Conclusions:

• Smartphone-based outdoor 6MWTs are valid, repeatable, and well-accepted by PAH patients.
• Further research is needed to confirm the clinical utility of app-based 6MWTs.
• Indoor app accuracy requires improvement for reliable clinical use.