6th vital sign app: Testing validity and reliability for measuring gait speed.

Area of Science:

• Biomedical Engineering
• Clinical Biomechanics
• Digital Health

Background:

• Gait speed is a key predictor of health outcomes.
• Smartphone applications offer convenient methods for health assessments.
• The 6th Vital Sign app aims to measure gait speed.

Purpose of the Study:

• To evaluate the validity and reliability of the 6th Vital Sign app for measuring gait speed.
• To compare the app's gait speed measurements against established methods.

Main Methods:

• Prospective test-retest design with 15 college subjects.
• Gait speed measured using the 6th Vital Sign app, Brower timing gates, and manual calculation.
• Criterion validity assessed via t-tests and correlations; inter-trial reliability assessed via correlations.

Main Results:

• The app significantly underestimated gait speed compared to timing gates and manual measurements.
• App measurements showed moderate correlation with gold-standard methods (r=0.365-0.370).
• High inter-trial reliability was observed for the app (r=0.916).

Conclusions:

• The 6th Vital Sign app demonstrates high reliability but lacks criterion validity for gait speed measurement.
• The app's tendency to underestimate speed precludes its use in clinical diagnosis or prognosis.
• Further research is needed to improve the accuracy of smartphone-based gait speed assessment tools.