Impact of mobility dose levels on functional outcomes in individualised patients with critical illness: A multicentre prospective observational cohort study in Japan

Objective To investigate the association between individualised rehabilitation dose levels and functional outcomes across age- and frailty-specific cohorts of critically ill patients. Design Multicentre prospective observational cohort study Setting Intensive care units at 22 hospitals in Japan. Participants Overall, 422 adult patients receiving mechanical ventilation for ≥48 h were categorised into old non-frail (age ≥65 years, clinical frailty scale: 1–4), old frail (age ≥65 years, clinical frailty scale: > 4) and middle-aged/young (age <65 years) cohorts. Main measures The primary outcome was independence in activity of daily living at hospital discharge, defined by a Barthel Index score of ≥90. Rehabilitation parameters dose, intensity, duration, frequency and timing were assessed. Multivariable logistic regression analysis was performed for each cohort. Results In the old non-frail cohort, activity of daily living independence was associate with higher dose (odds ratio: 1.10, 95% confidence interval: [1.04–1.17]), higher intensity (odds ratio: 1.18 [1.02–1.37]) and shorter time to first mobilisation (odds ratio: 0.92 [0.86–0.98]), whereas, in the old frail cohort, it was higher dose (odds ratio: 1.07 [1.02–1.18]), longer duration (odds ratio: 1.05 [1.01–1.12]) and higher frequency (odds ratio: 1.82 [1.07–4.62]). In the middle-aged/young cohort, activity of daily living independence was associated with higher dose (odds ratio: 1.14 [1.05–1.28]) and higher intensity (1.30 [1.06–1.62]). Conclusions The impact of rehabilitation dose on functional recovery varies across age- and frailty-specific cohorts. These findings highlight the importance of tailoring rehabilitation dose to patient characteristics to optimise functional outcomes in critical illness. Trial registration: UMIN000036503.