Assessing physical activity in persons with knee osteoarthritis using accelerometers: Data from the osteoarthritis initiative
Tóm tắt
Physical activity measured by accelerometers requires basic assumptions to translate the output into meaningful measures. We used accelerometer data from the Osteoarthritis Initiative to investigate in the context of knee osteoarthritis (OA) the following data processing assumptions derived from the general US adult population: nonwear (a period the monitor was removed), based on zero activity exceeding 60 minutes; and a valid day of monitoring, based on wear time evidence exceeding 10 hours.
We examined the influence of nonwear thresholds ranging from 20 to 300 minutes of zero activity on mean daily activity minutes (counts >0), mean daily activity counts, and mean daily moderate to vigorous physical activity minutes. The effect of selecting minimums of 8, 10, or 12 wear hours to signify a valid day of monitoring on data retention was examined.
Our sample of 3,536 days of accelerometer data from 519 persons with knee OA showed that mean daily activity minutes increased with the nonwear threshold until stabilizing at 463 minutes per day, corresponding to the 90‐minute nonwear threshold. Similar patterns were observed for mean daily activity counts. Varying the nonwear threshold had no effect on mean daily moderate to vigorous physical activity minutes. Choosing the 90‐minute nonwear threshold and a minimum of 10 wear hours to constitute a valid day provided 94% data retention.
Data supported applying the 90‐minute nonwear threshold to the knee OA population instead of the 60‐minute threshold for the general population, while retaining the 10‐hour valid day threshold.
Từ khóa
Tài liệu tham khảo
Centers for Disease Control and Prevention, 2007, Projected state‐specific increases in self‐reported doctor‐diagnosed arthritis and arthritis‐attributable activity limitations: United States, 2005‐2030, MMWR Morb Mortal Wkly Rep, 56, 423
Dillon CF, 2006, Prevalence of knee osteoarthritis in the United States: arthritis data from the Third National Health and Nutrition Examination Survey 1991‐94, J Rheumatol, 33, 2271
Chen KY, 1997, Improving energy expenditure estimation by using a triaxial accelerometer, J Appl Physiol, 83, 2112, 10.1152/jappl.1997.83.6.2112
National Cancer Institute, 2007, Risk factor monitoring and methods: SAS programs for analyzing NHANES 2003‐2004 accelerometer data
Welk GJ, 2004, Reliability of accelerometry‐based activity monitors: a generalizability study, Med Sci Sports Exerc, 36, 1637
2007, Stata/SE: version 10.0 for Windows
2009, Base SAS 9.2 procedures guide
Hirata S, 2006, Ambulatory physical activity, disease severity, and employment status in adult women with osteoarthritis of the hip, J Rheumatol, 33, 939
US Census Bureau. Table 1212: participation in selected sports activities. 2007: statistical abstract of the United States.2010. URL:http://www.census.gov/compendia/statab/2010/tables/10s1212.xls