Surrogates for rigidity and PIGD MDS-UPDRS subscores using wearable sensors.
Delaram Safarpour, Marian L Dale, Vrutangkumar V Shah and 4 others
PMID 34736096WHAT IT FOUND
In 31 people with mild to moderate Parkinson's, wearable sensor data predicted clinical rigidity and postural instability scores.
Rigidity was best estimated by the number of walking bouts, while postural instability required combining walking bouts, gait speed, and standing sway.
Key findings
01The number of walking bouts during daily life was the strongest single predictor for both total motor severity and the rigidity subscore.
02The postural instability and gait difficulty (PIGD) subscore was best predicted by a combination of walking bouts, gait speed, and sway area on a firm surface.
03These sensor-based predictions are not yet ready for use in telehealth or clinical trials and require validation in larger groups.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
Small sample size (31 participants) limits generalizability. All clinical assessments were done in the 'ON' medication state, so it is unclear how these sensors perform when medication wears off. Postural sway was measured in the laboratory, not at home, meaning the 'home-based' surrogate for PIGD is not fully validated for remote use. The study used a best-subset selection strategy which can overfit to small datasets, requiring larger validation studies. Patients could already walk without assistance, so findings may not apply to those with more advanced mobility limitations.
Declared interests
One author has a significant financial interest in APDM Wearable Technologies, the company that manufactured the sensors used in the study. Another author received consulting honoraria from Abbvie and Synergic Medical Technologies.
The easy way to misread this
Do not interpret these sensor measures as direct replacements for physical examination. The study found that rigidity was predicted by the number of walking bouts, not by a direct measurement of muscle stiffness. This implies that reduced activity is a proxy for rigidity in this context, not that the sensors measured rigidity itself.