Agreement between activPAL3c accelerometers placed at different thigh positions

Comparison of postoperative mobilization measurements by activPAL versus Johns Hopkins Highest Level of Mobility scale after major abdominal surgery

BACKGROUND

The Johns Hopkins Highest Level of Mobility scale is a validated tool for assessing patient mobility in the hospital. It has excellent inter-rater and test-retest reliabilities, but it is unknown how accurately Johns Hopkins Highest Level of Mobility documentation reflects the patients' mobility performance in the immediate postoperative period compared to objective measures such as accelerometers.

METHODS

In this single-center observational study, consented adults undergoing open abdominal surgery wore a research-grade accelerometer, activPAL, starting immediately postoperatively until hospital discharge or up to 7 days. We collected the Johns Hopkins Highest Level of Mobility scores documented by hospital staff via retrospective chart review and evaluated their accuracy in describing the type, frequency, and volume of postoperative out-of-bed mobilization using the activPAL as the criterion.

RESULTS

We analyzed data from 56 participants. The activPAL showed that participants spent 97.7% of their time lying in bed or sitting in a chair. Meanwhile, the Johns Hopkins Highest Level of Mobility documentation of preambulatory activities (scores 1-5) was rare. The activPAL detected 4 times more out-of-bed mobilization than routine Johns Hopkins Highest Level of Mobility documentation. Whereas the frequency of activPAL-measured out-of-bed mobilization increased steadily to a median of 9 sessions by postoperative day 6, the number of Johns Hopkins Highest Level of Mobility documentation remained around twice daily. ActivPAL measurements demonstrated that Johns Hopkins Highest Level of Mobility documentation of ambulatory sessions (scores 6-8) was accurate.

CONCLUSIONS

We found that routine Johns Hopkins Highest Level of Mobility documentation did not accurately detect preambulatory activities or the overall frequency of out-of-bed mobility sessions, poorly reflecting the highly sedentary behaviors of the acute postoperative inpatients and highlighting the need to improve clinical documentation or use alternative methods to track postoperative mobilization.

How many days are enough for measuring weekly activity behaviours with the ActivPAL in adults?

OBJECTIVES

The purpose of this study was to determine the number of monitoring days needed to reliably measure weekly activity behaviours with the ActivPAL (AP) monitor in adults.

DESIGN

Cross-sectional study.

METHODS

Participants (90 adults (51.1% men); age=39.1±12.43 years) wore an AP for 7 consecutive days. Mean time spent sitting/lying, standing and stepping per day, and mean number of transitions from sitting to standing per day were calculated for each participant using 7 days of monitoring (reference). Estimates for these activities were also derived from a combination of randomly selected days (from 1 to 6 days), and randomly selected weekdays and weekend days, and compared with the reference using ANOVA, correlation coefficients and Bland-Altman methods Spearman-Brown Prophecy Formula, based on Intraclass correlation of 0.8, was used to predict the minimum number of days needed to represent activity behaviours as measured with the AP.

RESULTS

At least five days of monitoring were necessary to achieve a reliability of 0.8 for all postures and transitions. Correlation coefficients between estimates derived from any combination of 5 days and the reference were high (rho=0.96-0.98). When using a combination of weekdays and weekend days, mean biases were comparable with those shown by any combination of days, but 95% limits of agreement were narrower.

CONCLUSIONS

When using the AP for a week, data from a combination of any 5 days provided reliable estimates of all activities and transitions per day, but more precise estimates were achieved if at least 1 weekend day was included.

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 by 25 (95% CI: -47, -3) seconds. The largest median absolute percent errors were for standing time (21.9%) and stepping time (18.7%); time spent upright (1.7%) or sedentary (0.3%) was more accurately estimated. The activPAL underestimated total steps per session, achieving the largest percent error (70.8%). Conclusion: Because it underestimated step count, the activPAL likely incorrectly recorded stepping time as standing time, so that time spent upright was the measure of activity with the smallest error. Sedentary behaviour, including frequency of transitions, was validly assessed.