Elderly Activity Life-Space Envelopes (EASE): Development and Feasibility of a Comprehensive, Integrated Protocol for Life-Space Mobility Research in Population Health.

Background: Life-space mobility (LSM) refers to the movement of people over time and the areas through which they move to achieve life goals of health, employment, security, and participation for active aging. Objective: The Elderly Activity Life-Space Envelopes program is a large interdisciplinary mixed methods LSM study in older adults of 50 years and above. The overarching aims were to discover why, where, and when older adults travel and how they get to their destinations. Methods: In this paper, we focus on the methodology of the main quantitative phase. This community-based study comprised an in-person multidomain geriatric assessment with physical performance measures, followed by a 14-day travel diary. For the multidomain geriatric assessment, we structurally underpinned important population health constructs including the WHO International Classification of Functioning, Disability and Health, Frailty, and Intrinsic Capacity. We also described home meso-environments by incorporating authoritative open-source environmental attributes. These facilitated the categorization of LSM determinants into health, social, and environmental domains. The LSM outcomes include self-reported and objective geographical information science LSM measures. We further developed a suite of geographical information science LSM outcomes in alignment with our overarching aims. Quota sampling based on age groups, housing typology, and frailty status was applied. A customized, smartphone-based digital travel diary was designed, and barometric sensors were enabled to capture 3D LSM in capable smartphones. Results: We recruited 1131 older adults with an average age of 63.8 (SD 7.6) years. The large majority (n=1062, 95%) successfully documented their travel diary on their smartphones with the rest on paper-based travel diaries. For the digital data, a total of 88,166 node points were recorded. There were 76,741 trips and 106,323 trip legs documented through the e-travel diary platform. Valid vertical LSM data were obtained from 228 participants. The majority (n=842, 75%) lived in public apartments, and 29% (n=326) were prefrail or frail. Conclusions: We provide a practical, feasible yet comprehensive protocol integrating LSM within important population health themes. Also, the development of an objective, systematic outcomes framework will form the basis for future LSM studies in the field. We aim to analyze the interactions between LSM outcomes, explore its diverse determinants, and identify senior travel phenotypes. We hope to develop interdisciplinary policy-driven interventions to ultimately improve the quality of life in older adults.