Free-living gait cadence measured by wearable accelerometer: a promising alternative to traditional measures of mobility for assessing fall risk

Background Wearable devices have become widespread in research applications, yet evidence on whether they are superior to structured clinic-based assessments is sparse. In this manuscript, we compare traditional, lab-based metrics of mobility with a novel accelerometry-based measure of free-living gait cadence for predicting fall rates. Methods Using negative binomial regression, we compared traditional in-clinic measures of mobility (6-minute gait cadence, speed, and distance, and 4-meter gait speed) with free-living gait cadence from wearable accelerometers in predicting fall rates. Accelerometry data were collected with wrist-worn Actigraphs (GT9X) over 7 days in 432 community-dwelling older adults (aged 77.29±5.46 yrs, 59.1% men, 80.2% White) participating in the Study to Understand Fall Reduction and Vitamin D in You (STURDY). Falls were ascertained using monthly calendars, quarterly contacts, and ad-hoc telephone reports. Accelerometry-based free-living gait cadence was estimated with the Adaptive Empirical Pattern Transformation algorithm. Results Across all participants, free-living cadence was significantly related to fall rates; every 10 steps/min. higher cadence was associated with a 13.2% lower fall rate (p=0.036). Clinic-based measures of mobility were not related to falls (p>0.05). Among higher-functioning participants (cadence ≥100 steps/min.), every 10 steps/min higher free-living cadence was associated with a 27.7% lower fall rate (p=0.01). In participants with slow baseline gait (gait speed <0.8 m/s), all metrics were significantly associated with fall rates. Conclusion Data collected from biosensors in the free-living environment may provide a more sensitive indicator of fall risk than in-clinic tests, especially among higher functioning older adults who may be more responsive to intervention.