Global Positioning System Indicators of Community Mobility and Future Health Outcomes Among Older Adults

Background: We examined the relationship between global positioning system (GPS) indicators of community mobility and incident hospitalizations, emergency department (ED) visits, and falls over 1-year in community-dwelling older adults. Methods: We performed a secondary analysis of a randomized trial investigating a physical therapy intervention to improve mobility in older adults. One hundred and forty-eight participants (mean age: 76.9 ± 6.2 years; 65% female) carried a GPS device following the postintervention visit. Over 1-year, new hospitalizations, falls, and ED visits were reported. GPS indicators of community mobility included the median area and compactness of the standard deviation ellipse (SDE), the median percentage of time spent outside of home (TOH), and median maximum distance from home. Generalized linear models assessed the association between 1-year risk of outcomes and GPS measures adjusted for age, race, gender, body mass index, comorbidity burden, and fall history. Results: The mean ± standard deviation of the median SDE area was 4.4 ± 8.5 km², median SDE compactness 0.7 ± 0.2, median percentage TOH 14.4 ± 12.0%, and median maximum distance from home was 38 ± 253 km. Each 5% increase in median percentage TOH was associated with a 24% lower risk of hospitalization (incident rate ratio = IRR = 0.76, 95%CI: 0.61–0.95; p = .01). The association persisted after covariate adjustment (IRR = 0.78, 95%CI: 0.63–0.98; p = .03). No significant associations appeared for any GPS indicators with incident falls or ED visits. Conclusions: Increased TOH was associated with a lower risk of incident hospitalization over 1 year among community-dwelling older adults. Restricted community mobility may be an indicator of activity limitations related to future health outcomes, but further study is warranted.