Using GPS Technologies to Examine Community Mobility in Older Adults

Background Objective measures of community mobility are advantageous for capturing movement outside the home. Compared with subjective, self-reported techniques, global positioning system (GPS) technologies leverage passive, real-time location data to reduce recall bias and increase measurement precision. We developed methods to quantify community mobility among community-dwelling older adults and assessed how GPS-derived indicators relate to clinical measures of physical and cognitive performance. Methods Participants (n = 149; M +/- standard deviation [SD] = 77.1 +/- 6.5 years) from the program to improve mobility in aging (PRIMA) study, a physical therapy intervention to improve walking ability, carried a GPS device for 7 days. Community mobility was characterized by assessing activity space, shape, duration, and distance. Associations between GPS-derived indicators and cognition and physical function were evaluated using Spearman correlations. Results In adjusted models, a larger activity space, greater duration (eg, time out-of-home), and greater distance traveled from home were correlated with better 6-Minute Walk Test performance (rho = 0.17-0.23, p's < .05). A more circular activity shape was related to poorer performance on the Trail Making Test, Part A (rho = 0.18, p < .05). More time out-of-home and a larger activity space were correlated with faster times on the Trail Making Test, Part B (rho = -0.18 to -0.24, p's < .05). Community mobility measures were not associated with global cognition, skilled walking, or usual gait speed. Conclusion GPS-derived community mobility indicators capture real-world activity among older adults and were correlated with clinical measures of executive function and walking endurance. These findings will guide the design of future interventions to promote community mobility.