Daily Total Physical Activity and Hospitalization or Death in Older Adults in Assisted Living Residences: An Exploratory Cohort Study Using Two ActivPAL Accelerometers in Japan

Older adults in assisted living residences spend most of their time engaged in sedentary activities. However, the relationship between physical activity, sitting time, or lying time and hospitalization and mortality in older adults remains unclear. Therefore, the present study aimed to evaluate the relationship between physical activity and hospitalization or death among older adults in assisted living residences. This exploratory prospective study included older adults in assisted living residences in Japan. Using two ActivPAL accelerometers attached to the chest and thigh, we assessed physical activity and posture, including lying down, sitting, standing, and stepping. The participants were followed up for 2-2.5 years. The primary outcome was a composite outcome, including all-cause hospitalization and mortality in a time-to-event analysis. Of 112 residents in two facilities, 35 patients were assessed using ActivPAL accelerometers. The primary outcome was observed in 22 of 19,154 person-days. The median values of the step count, upright time, sitting time, and lying down time were 1,004 steps, 149.5 min, 563.8 min, and 729.3 min, respectively. An upright time of <150 min/day significantly increased the risk of hospitalization and mortality compared with an upright time of >150 min daily. Upright time may be an important indicator of physical activity and posture in older adults in assisted living residences. Upright time of >150 min daily for older adults in assisted living residences might be an essential key affecting hospitalization and mortality; encouraging older adults to spend time outside their rooms may be beneficial.