Validity of Smartphone-Based Measurement for Assessing Lower Limb Power for Sarcopenia and Frailty Discrimination:...

Area of Science:

• Gerontology
• Biomedical Engineering
• Digital Health

Background:

• Aging populations necessitate focus on age-related conditions like sarcopenia and frailty.
• Early detection and intervention are critical for managing these conditions and reducing long-term care needs.

Purpose of the Study:

• To validate a smartphone-based system for measuring sit-to-stand (STS) movement acceleration.
• To assess the system's efficacy in detecting sarcopenia and frailty.

Main Methods:

• 587 community-dwelling older adults performed STS trials with a smartphone on the lower abdomen.
• Sarcopenia and frailty diagnosed using established criteria.
• Acceleration signals analyzed for peak force, rising time (T1), and stabilization time (T2).
• Reproducibility assessed via intraclass correlation coefficient (ICC).
• Predictive models developed and compared against benchmark models (age, sex, walking speed, grip strength).

Main Results:

• Smartphone model achieved an AUC of 0.781 for sarcopenia detection, outperforming walking speed and age/sex.
• For frailty, the smartphone model showed moderate discrimination (AUC 0.659), exceeding age/sex.
• Peak force measurement demonstrated excellent reliability (ICC=0.863).
• T1 and T2 showed lower reproducibility (ICC<0.30).

Conclusions:

• Smartphone-derived STS acceleration is a practical, scalable method for screening sarcopenia and frailty in older adults.
• This technology complements traditional measures like grip strength and walking speed.
• It supports large-scale functional screening and early detection initiatives in aging societies.