Use of Fitbit Activity Monitor Successfully Assessed Transfemoral Amputee Activity Levels

Use of the Medicare Functional Classification Level for the classification of the functional capabilities of amputees is often limited by assessment techniques that can be administered in a clinical setting. In a recent feasibility study, researchers used Fitbit activity monitors to successfully assess the activity levels of transfemoral amputees. This technique may be useful in providing insight into prosthetic use in an at-home environment.

“The purpose of the study was to assess the mobility of people with transfemoral amputations using data collected from a popular, consumer-oriented activity monitor,” Mark V. Albert, PhD, assistant professor in the computer science department at Loyola University Chicago, told O&P Business News. “Although validated, research-grade monitors exist for this purpose, the low cost, wide availability and direct-to-consumer design of this class of activity monitors brings distinct advantages in adoption by clinics and individuals.”

Use of Fitbit activity monitors

Nine transfemoral amputees, including seven K3, one K2 and one K4 level patients, wore Fitbit One activity monitors on the belt or waistband for 1 week. Main outcome measures included daily estimates of step counts, distance walked, floors/stairs climbed, calories burned and proprietary Fitbit activity scores. Researchers also collected the amount of time each day participants were sedentary, lightly active, fairly active and highly active.

Mark V. Albert

Mark V. Albert

Researchers observed a likely trend between percent of movement time above the fairly active level and designated K-level. Patients who were obese had decreased levels of activity. Study results also showed step counts and miles walked were redundant when stride lengths were not specified. Using linear regression prediction models, researchers found calorie estimates were highly dependent on patient age, height and weight after estimated measures of activity, such as steps and floors climbed, were included. However, the Fitbit proprietary activity score trended with these activity measures but was independent of all three demographic factors for this sample.

“The trend of activity to the K-level designations was more robust than we had anticipated,” Albert, who is also an adjunct professor in the Department of Physical Medicine and Rehabilitation at Northwestern University, said. “Typically in feasibility studies this small we see greater effects of random variation, so we expect this trend to be strong in larger scale follow-up studies. This suggests a likely ability to predict K-level from these worn activity monitors.”

Follow-up study

According to Albert, the implementation of a follow-up study would collect more individuals across the K-level designation spectrum and allow researchers to better observe the trend between K-level and activity. If the follow-up study shows a strong correlation, it would suggest the Fitbit is a useful diagnostic tool which could help re-evaluate an individual’s K-level “or a rethinking of the decision criteria that are used clinically.

“It is difficult to collectively measure how active individuals are as a population. Calories are highly dependent on weight, and step counts are dependent on stride length. By considering proprietary measures such as the Fitbit activity score, or a more open standard with a similar purpose, it would be easier to collect information on patient activity across a population,” Albert said. “We would expect more clinical practices, especially those with limited budgets and large populations, to encourage patients to use less expensive, consumer-grade devices. Although they clearly do not meet the strict standards of research-grade, validated devices, there are fewer barriers to adoption. We hope work like this brings about an increased use of objective activity metrics when research-grade monitors are not feasible.” — by Casey Tingle

For more information:
Albert MV. PM R. 2014;doi:10.1016/j.pmrj.2014.06.006.

Disclosure: Funding for this study was provided by the Max Nader Center at the Rehabilitation Institute of Chicago.

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