Background: Hospital-acquired disability (HAD) is common, and a key contributor to this process is low hospital physical activity. This study examines whether objective measures of hospital physical activity from wearable accelerometers can be used to predict HAD.
Methods: Prospective observational study of community-dwelling older adults aged ≥ 60 years, admitted to an academic hospital’s general medicine service from January 2016-March 2017, and enrolled within 24 hours of admission. Hospital activity was measured using ankle-mounted accelerometers from admission until discharge (or ≤ 7 days). Primary outcome was HAD, determined by self-reported ability to perform 1) Katz’s activities of daily living (ADL), (score range 0-5), and 2) broader functional activities using the Late-Life Functional and Disability instrument (FDI) (score range 15-75). HAD was defined as having one or more new ADL deficits, decline of 4 or greater on the Late-Life FDI, calculated between baseline and discharge, or discharge to skilled nursing facility (SNF). Relationships between hospital physical activity measures (mean active time (hrs/day); mean sedentary time (awake but not moving, hrs/day); mean step counts per day; and a 900 steps/day threshold) and HAD were examined with bivariate and logistic regression analyses.
Results: We approached 210 eligible patients and 79 enrolled. Patients were excluded due to incomplete accelerometer data (n=14), or missing discharge functional data (n=17). Among 48 patients with complete data, mean age was 73.2 years (SD 9.5), 48% were male, 77% were Caucasian. Median length of stay was 4 days (IQR 2.0, 6.0)); 62% (n=40) reported being able to walk without assistance at baseline. HAD rate was 42% (n=20); 25% (n=12) had a self-reported decline in function and 17% (n=8) were discharged to SNF. Those with HAD had lower activity time (0.9 hrs/day vs. 1.6 hrs/day, p=0.02), and lower step counts (1402 steps/day vs. 2235 steps/day, p=0.04), but no difference in sedentary time, compared to those without HAD. Overall, 25% (n=12) walked < 900 steps/day, of these, 67% (n=8) developed HAD, representing a 2 fold increased risk of developing HAD (RR 2.0, 1.1-3.7).
Conclusions: Accelerometer-based measures of hospital physical activities are associated with a clinically meaningful patient outcome; hospital acquired disability. Clinicians could use wearable technology in mobility enhancement interventions to appropriately target physical /occupational therapy or walking programs, monitor adherence to activity recommendations, and assess patient recovery.