Comparing three wearable accelerometers to measure early activity after cardiac surgeryCentral MessagePerspective
Charles H. Brown, IV, MD, MHS,
Lisa Yanek, MPH,
Ryan Healy, BA,
Tiffany Tsay, MPH,
Junrui Di, PhD,
Lee Goeddel, MD, MPH,
Daniel Young, PT, DPT, PhD,
Vadim Zipunnikov, PhD,
Jennifer Schrack, PhD, MS,
Glenn Whitman, MD,
Kaushik Mandal, MD,
Tim Madeira, CRNP,
Michael C. Grant, MD, MSE,
Erik H. Hoyer, MD
Affiliations
Charles H. Brown, IV, MD, MHS
Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Md; Address for reprints: Charles H. Brown, IV, MD, MHS, Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University School of Medicine, Zayed 6208, 1800 Orleans St, Baltimore, MD 21210.
Lisa Yanek, MPH
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Md
Ryan Healy, BA
Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Md
Tiffany Tsay, MPH
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Md
Junrui Di, PhD
Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Md
Lee Goeddel, MD, MPH
Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Md
Daniel Young, PT, DPT, PhD
Department of Physical Therapy, University of Nevada, Las Vegas, Las Vegas, Nev
Vadim Zipunnikov, PhD
Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Md
Jennifer Schrack, PhD, MS
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Md
Glenn Whitman, MD
Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md
Kaushik Mandal, MD
Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md
Tim Madeira, CRNP
Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md
Michael C. Grant, MD, MSE
Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Md
Erik H. Hoyer, MD
Department of Physical Therapy, Johns Hopkins University School of Medicine, Baltimore, Md
Objective: Wearable activity monitors can provide detailed data on activity after cardiac surgery and discriminate a patient's risk for hospital-based outcomes. However, comparative data for different monitoring approaches, as well as predictive ability over clinical characteristics, are lacking. In addition, data on specific thresholds of activity are needed. The objective of this study was to compare 3 wearable activity monitors and 1 observational mobility scale in discriminating risk for 3 hospital-based outcomes, and to establish clinically relevant step thresholds. Methods: Cardiac surgery patients were enrolled between June 2016 and August 2017 in a cohort study. Postoperative activity was measured by 3 accelerometry monitors (StepWatch Ambulation Monitor, Fitbit Charge HR, and ActiGraph GT9X) and 1 nurse-based observation scale. Monitors represent a spectrum of characteristics, including wear location (ankle/wrist), output (activity counts/steps), consumer accessibility, and cost. Primary outcomes were duration of hospitalization >7 days, discharge to a nonhome location, and 30-day readmission. Results: Data were available from 193 patients (median age 67 years [interquartile range, 58-72]). All postoperative day 2 activity metrics (ie, from StepWatch, Fitbit, ActiGraph, and the observation scale) were independently associated with prolonged hospitalization and discharge to a nonhome location. Only steps as measured by StepWatch was independently associated with 30-day readmission. Overall, StepWatch provided the greatest discrimination (C-statistics 0.71-0.76 for all outcomes). Step thresholds between 250 and 500 steps/day identified between 74% and 96% of patients with any primary outcome. Conclusions: Data from wearable accelerometers provide additive value in early postoperative risk-stratification for hospital-based outcomes. These results both support and provide guidance for activity-monitoring programs after cardiac surgery.
