Physical Activity of ICU Survivors during Acute Admission: Agreement of the activPAL with Observation

Purpose: We estimated the agreement of a thigh-worn accelerometer, the activPAL, used to measure activity and sedentary parameters, with observed mobility assessments of intensive care unit (ICU) survivors. Method: We prospectively compared activPAL measurements with direct observation during assessments at discharge from the ICU or acute hospital in eight participants with a median age of 56 (1st–3rd quartile 48–65) years and an Acute Physiology and Chronic Health Evaluation II score of 23 (1st–3rd quartile 17–24). Frequency of sit-to-stand transitions; time spent standing, stepping, upright (standing and stepping), and sedentary (lying/sitting); and total steps were described; analysis was performed using Bland–Altman plots and calculating the absolute percent error. Results: All sit-to-stand transitions were accurately detected. The mean difference on the Bland–Altman plots suggested an overestimation of standing time with the activPAL of 31 (95% CI: −9, 71) seconds and underestimation of stepping time...