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.