|
 The study tested four popular wristbands, each of which has a
light-emitting diode (LED) that measures heart rate from tiny
changes in skin blood volumes by using light reflected from the
skin.
Participants in the study - 40 healthy adults - wore two trackers on
each wrist and compared resting and exercise heart rate readings on
the devices to the gold standard used by doctors: an
electrocardiogram (ECG or EKG) test.
At rest, the Fitbit Surge got heart rate measurements that most
closely matched the ECG results, and the Basis Peak was furthest
off. In tests that also included the Fitbit Charge and Mio Fuse,
none of the trackers got exercise heart rate readings that came
close to the ECG.
These results suggest that while the trackers may help monitor daily
activity, it’s not clear the heart rate readouts would be accurate
enough to help patients with certain health problems make medical
decisions, the authors note in Annals of Internal Medicine.
“At any moment, the tracker could be off by a fair bit, but at most
moments, it won’t be," said lead study author Lisa Cadmus-Bertram of
the University of Wisconsin in Madison.
“This is why our paper doesn’t suggest that the commercial trackers
we tested would be sufficient for medical applications where high
precision is needed during exercise,” Cadmus-Bertram said by email.
“Yet for the typical recreational user, they may still provide
feedback that’s useful and motivational.”
To assess the accuracy of the trackers, researchers examined heart
rate data for participants who were 49 years old on average and
slightly overweight.
First, they looked at the amount of agreement between the readings
from the trackers and the ECG tests.
When participants were seated, researchers took readings for the
trackers and the ECG tests at one-minute intervals for 10 minutes.
The narrowest range of differences between the trackers and the ECG,
indicating the most accuracy, was for the Fitbit Surge. The range
for this tracker ranged from an underestimation of 5.1 beats per
minute to an overestimation of 4.5 beats per minute.
The widest range of difference at rest was for the Basis Peak, which
ranged from an underestimation of 17.1 beats per minute to an
overestimation of 22.6 beats per minute.
When participants exercised on a treadmill, the ranges were even
wider. The Mio Fuse ranged from an underestimation of 22.5 beats per
minute to an overestimation of 26 beats per minute, for example,
while the Fitbit Charge range from an underestimation of 41 beats
per minute to an overestimation of 36 beats per minute.
The study is small, and researchers found only limited repeatability
with results for the same participant under the same conditions.
[to top of second column] |
Still, the findings are an important first step in understanding the
clinical validity of wrist trackers many patients already use, said
Dr. Daniel Cantillon, a researcher at the Cleveland Clinic in Ohio
who wasn’t involved in the study.
“We need data testing these devices among patients with specific
disease states, such as heart failure, atrial fibrillation and other
chronic medical problems, where it is possible that additional
variation will occur with physical activity,” Cantillon said by
email.
In particular, patients with the most common heart rhythm disorder,
atrial fibrillation, shouldn’t rely on the trackers to detect
abnormal rhythms, said Dr. Sumeet Chugh, a researcher at
Cedars-Sinai Heart Institute in Los Angeles who wasn’t involved in
the study.
“There is a lot at stake here,” Chugh said by email. “When it comes
to the use of wrist-worn trackers, we need to be confident of
accuracy comparable to treadmill testing if we are going to use the
information for patient care.”
A spokesperson for Fitbit told Reuters Health that Fitbit trackers
"are not intended to be medical devices” but instead “to give a more
informed picture" of overall health. "Extensive internal studies . .
. show that Fitbit’s PurePulse technology performs to industry
standard expectations for optical heart rate on the wrist,” the
spokesperson said.
Mark Gorelick, Chief Science Officer at Mio Global, said in a
statement that the company's technology "helps consumers understand
the intensity of their exercise, based on their personal profile and
heart rate data, and empowers them to proactively manage their
health and reduce risk of lifestyle-related diseases.”
SOURCE: http://bit.ly/2p0mN0u Annals of Internal Medicine, online
April 10, 2017.
[© 2017 Thomson Reuters. All rights
reserved.] Copyright 2017 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.
 |
