Agreement Between Activpal And Actigraph Accelerometers On Hourly Movement Behaviors Among Adults With Knee Replacement

Abstract

PURPOSE: To examine the agreement between the activPAL and ActiGraph accelerometers for measuring sedentary, light, moderate-to-vigorous activity minutes and step counts for adults following knee replacement. A secondary aim was to compare differences in the agreement between the accelerometers at ~1 and 3 months after surgery. METHODS: Participants with knee replacement from a randomized physical activity intervention wore activPAL and ActiGraph monitors simultaneously at the start of outpatient physical therapy (32.5 ± 9.5 days after surgery) and 3 months post-surgery. Only days with ≥10 hours/day of wear time from both monitors concurrently were included. The intraclass correlations (ICCs) for hourly minutes spent in sedentary, light, and moderate-to-vigorous physical activity and steps were used to compare the agreement between monitors. Additionally, ICCs were compared between 1 and 3 months. RESULTS Four hundred and eighty day-matched observations from 41 participants (64.9 ± 7 years, 75.6% White, 61% female) were included. The ICC between accelerometers was 0.839 for sedentary behavior, 0.853 for light physical activity, 0.806 for moderate-to-vigorous physical activity, and 0.937 for steps. These ICCs were significantly higher at 3 months as compared to 1 month (Table 1). CONCLUSIONS Our results demonstrate that the agreement between monitors were high for sedentary, light, moderate-to-vigorous minutes, and steps, with the highest agreement for step counts. Interestingly, the correlation was higher at 3 months as compared to 1-month post-op. These results suggest that the two monitors may be used interchangeably to assess hourly movement behaviors among adults with knee replacement; however, caution is warranted for use within a month after surgery.