Mobility During an Acute Medical Hospitalization: A Prospective Cohort Study.

Objectives We aimed (1) to describe changes in daily activity proportion, (2) to describe mobility during an acute hospitalization, and (3) to assess their associations with institutionalization and survival within 3 months. Design Secondary analysis of a randomized controlled trial. Setting And Participants Adult patients hospitalized on general internal medicine wards of a Swiss tertiary hospital (September 2021-April 2023) with an expected hospital stay ≥5 days. Daily activity was continuously measured using accelerometers; mobility was assessed with the de Morton Mobility Index at least twice before discharge. Methods Predictors of change in daily activity proportion and mobility from admission to discharge were identified using logistic regression. Longitudinal changes during hospitalization were analyzed using adjusted linear mixed-effects models. Results A total of 162 participants were included. Daily activity proportion increased between admission and discharge in 51 of 137 patients (37%) with valid recordings. Repeated measures showed a small linear increase in activity over time, and daily activity proportion was associated with baseline de Morton Mobility Index scores (per 10-point increase: β = 0.005; 95% CI, 0.004-0.005; P < .001). Mobility improved in 81 of 126 patients (64%) between admission and discharge. Higher baseline Barthel Index for Activities of Daily Living scores and absence of mobility aids were associated with higher mobility levels (P < .001). In longitudinal analysis, mobility improved primarily during the first week but stagnated or declined thereafter, particularly among older patients. Increased daily activity proportion was associated with a higher likelihood of living at home 3 months after discharge; mobility was not. Neither was associated with survival. Conclusions And Implications Daily activity and mobility change differed during hospitalization and are associated with distinct outcomes. The observed plateau in mobility after 1 week of hospitalization suggests a critical window for targeted interventions, particularly in older patients with prolonged stays.