Accuracy of consumer-based activity trackers as measuring tool and coaching device in patients with COPD and healthy controls

Abstract

Background Consumer-based activity trackers are used to measure and improve physical activity. However, the accuracy of these devices as clinical endpoint or coaching tool is unclear. We investigated the use of two activity trackers as measuring and coaching tool in patients with Chronic Obstructive Pulmonary Disease (COPD) and healthy age-matched controls. Methods Daily steps were measured by two consumer-based activity trackers (Fitbit Zip, worn at the hip and Fitbit Alta, worn at the wrist) and a validated activity monitor (Dynaport Movemonitor) in 28 patients with COPD and 14 healthy age-matched controls for 14 consecutive days. To investigate the accuracy of the activity trackers as a clinical endpoint, mean step count per patient were compared with the reference activity monitor and agreement was investigated by Bland-Altman plots. To evaluate the accuracy of activity trackers as coaching tool, day-by-day differences within patients were calculated for all three devices. Additionally, consistency of ranking daily steps between the activity trackers and accelerometer was investigated by Kendall correlation coefficient. Results As a measuring tool, the hip worn activity tracker significantly underestimates daily step count in patients with COPD as compared to DAM (mean±SD Δ-1112±872 steps/day; p<0.0001). This underestimation is less prominent in healthy subjects (p = 0.21). The wrist worn activity tracker showed a non-significant overestimation of step count (p = 0.13) in patients with COPD, and a significant overestimation of daily steps in healthy controls (mean±SD Δ+1907±2147 steps/day; p = 0.006). As a coaching tool, both hip and wrist worn activity tracker were able to pick up the day-by-day variability as measured by Dynaport (consistency of ranking resp. r = 0.80; r = 0.68 in COPD).

Measurement properties of device-based physical activity instruments in ambulatory adults with physical disabilities and/or chronic diseases: a scoping review

“…In total, 23 different physical disabilities and/or chronic diseases were included in the studies. Most studies included people with stroke ( n = 27) [ 40 – 66 ], chronic obstructive pulmonary disease ( n = 11) [ 67 – 77 ] and multiple sclerosis ( n = 10) [ 78 – 87 ]. Six studies included a mixed population of people with different physical disabilities and/or chronic diseases [ 23 , 75 , 77 , 88 – 90 ].…”

“…Sample sizes ranged from 4 to 176, with a median of 28. The majority of studies were performed in Northern America (USA, n = 28 [ 51 , 64 , 69 , 70 , 72 , 74 , 76 , 83 – 85 , 91 – 107 ]; Canada, n = 10 [ 40 , 47 , 50 , 52 , 53 , 89 , 108 – 111 ]) and Western Europe (UK, n = 11 [ 78 , 80 , 82 , 86 , 112 – 118 ]; France, n = 8 [ 42 – 45 , 55 , 119 ]; the Netherlands, n = 6 [ 48 , 75 , 77 , 120 – 122 ]; Germany, n = 4 [ 68 , 87 , 123 , 124 ]; Switzerland, n = 4 [ 66 , 81 , 125 , 126 ]; Denmark, n = 3 [ 127 – 129 ]; Belgium, n = 2 [ 67 , 88 ]; Italy, n = 2 [ 56 , 130 ]; Sweden, n = 2 [ 71 , 79 ]; Ireland, n = 1 [ 131 ]; Portugal, n = 1 [ 132 ]). Only 14 studies were performed in other countries (Brazil, n = 6 [ 46 , 49 , 57 , 62 , 63 , 133 ]; Japan, n = 4 [ 59 , 73 , 134 , 135 ]; Australia, n = 3 [ …”

A Detailed Description of Physical Activity Counseling Interventions to Support Physical Activity in People With Chronic Obstructive Pulmonary Disease

“…Several studies have noted that only approximately 50% of the time will a Fitbit device provide accurate step measurement in controlled settings compared with research-grade devices 55. A recent study of consumer-grade activity tracker accuracy in people with COPD showed that the Fitbit Zip, worn at the hip, had a statistically significant underestimation of daily step count, and the Fitbit Alta, worn at the wrist, had a nonsignificant overestimation of daily step count 56. Clinicians may consider checking the accuracy of individual patients' personal devices, for instance, in comparison to actual steps taken during a session, to verify physical activity measures, especially for people with COPD, who have slower gait speeds.…”

The association of weather conditions with day-to-day variability in physical activity in patients with COPD

“…Patients were instructed to wear a wrist- or waist-worn activity tracker (Fitbit, San Francisco, CA, USA) on a daily basis during waking hours for 12 months. This step counter is valid to identify day-by-day changes in patients with COPD [ 10 ]. Data on daily step count were collected through the coaching smartphone application (m-PAC, AppsOnly).…”