By Deborah Gage
The explosion in smart devices -- phones, watches, fitness
gadgets and the like -- has unleashed a wave of apps designed to
manage chronic illnesses, detect behavioral diseases and manage
pain. Most recently, Apple announced that apps due later this year
will allow its Series 4 watches to perform electrocardiogram
readings, or ECGs, and notify users of irregular heart rhythms.
The problem for consumers is knowing which apps -- if any --
actually work.
The Food and Drug Administration cleared the ECG app and
irregular-rhythm notification feature on the Apple watch, but noted
that the apps aren't intended to replace traditional diagnosis
methods. The agency said the ECG data displayed on the Apple watch
is for informational purposes only and isn't intended to be
interpreted by the user without consulting a health-care
professional.
Most apps on the market lack approval from the FDA, which hasn't
been able to keep up with the health apps being released, raising
concerns that some apps could expose consumers to harm.
The FDA last September started working with Apple and eight
other tech and medical-device companies -- including Fitbit,
Samsung and Verily Life Sciences, a subsidiary of Google parent
Alphabet -- to streamline approval of mobile medical apps. In the
meantime, here is a status check on some of the areas where
health-monitoring tools might make the most difference.
Measuring Heart Health
Smartphones and watches can collect data on the heart
continuously, which promises to improve detection and treatment of
heart disease.
For instance, devices that track heartbeat data can help doctors
identify atrial fibrillation, a leading cause of heart failure and
strokes. With a-fib, the upper two chambers of the heart beat
erratically and at dangerously high speeds. Since symptoms come and
go, it can be hard to detect, but watches worn for long periods
have a chance of spotting it outside of a doctor's office.
An ECG, the standard method of detecting a-fib, requires placing
12 electrodes on a patient's body. The Apple Watch Series 4 will
have electrodes built into the watch's digital crown, which users
touch for 30 seconds after opening the app to get an ECG reading,
Apple says.
Another device, the KardiaBand watchband, also offers ECG
capabilities and was cleared by the FDA in November. It was most
effective in detecting a-fib when physicians looked at the results,
rather than relying solely on the watch's algorithms, according to
a study by the Cleveland Clinic. The device's instructions tell
wearers to place their thumb over a spot on the watchband embedded
with an electrocardiogram sensor, which records their heart
rhythm.
But in the Cleveland Clinic study, about 35% of the recordings
couldn't be read by the watch's algorithms, possibly because people
didn't press their thumbs down for the required 30 seconds.
Electrophysiologists, however, looking at the same data, were able
to accurately identify people with a-fib 100% of the time and
people without a-fib 80% of the time. The electrophysiologists also
beat the algorithm's performance on recordings that it could read,
correctly identifying people with a-fib 99% of the time, compared
with the algorithm's 93%.
"It's a reminder for all of us in dealing with digital health
that the patient is an active component of the equation and is part
of the end results on how good these recordings are," says Khaldoun
Tarakji, an electrophysiologist who led the study. Dr. Tarakji says
that with smartphone-based electrocardiogram monitors, the clinic
can access recordings of patients' heart rhythms no matter where
they are. Doctors can also use the monitors to diagnose patients
with intermittent episodes of a-fib, which are hard to catch, and
follow up on patients who have had ablations, a procedure that
removes diseased tissue from the heart to try to stop a-fib
symptoms.
Another new tool on the market is machine-learning software
called DeepHeart, which takes heart-rate, step-count and other data
from an Apple Watch or similar device and calculates the risk that
the wearer has one of several ailments, including a-fib, sleep
apnea, hypertension or diabetes, according to Brandon Ballinger,
co-founder of Cardiogram Inc., the company that built the software.
DeepHeart's diagnostic tests have FDA clearance, a status the
agency assigns to tools that it determines are "substantially
equivalent to another legally marketed device."
For Apple Watch wearers, DeepHeart was 97% accurate in
predicting a-fib for patients who had already been diagnosed (using
an electrocardiogram, the standard for diagnosis) and were
hospitalized for treatment, according to a study published earlier
this year by Mr. Ballinger and researchers at the University of
California, San Francisco. But it was only 72% accurate for
patients who thought they had a-fib but hadn't been diagnosed and
hospitalized, the study said.
Outside the hospital, in what Cardiogram calls "the real world,"
detecting a-fib is much harder, the company says. Motion, sweat and
sunscreen can affect how successfully an Apple Watch, for instance,
reads heartbeats. (Apple Watches have optical sensors which shine
light into your wrist and measure how much light is absorbed.
Between heartbeats, less blood flows, so less light is absorbed).
Alcohol consumption and exercise also affect heart rate and can
mask or mimic a-fib. Tests were conducted on earlier versions of
the Apple Watch, through Series 2, but Cardiogram is now also
compatible with Garmin and Android devices, Mr. Ballinger says.
Glucose Monitor
For more than 50 years, researchers have looked for ways to
monitor glucose that don't require people to prick their fingers
and draw blood. Bodily fluids including urine, sweat, saliva,
ocular fluids like tears, and interstitial fluids, which bathe
cells, also contain glucose and are easier to get to than blood.
But they can be challenging to work with.
Several companies are investigating minimally invasive or
noninvasive glucose monitors, and a few have been approved by the
FDA, but developing systems that don't penetrate the skin has been
challenging.
A glucose monitor from Dexcom Inc. that the FDA authorized for
marketing in March uses a sensor about the width of a human hair
that sits just under the skin and detects glucose in the
interstitial fluid. It generates an electrochemical signal that's
read by a processor and converted into data that's transmitted to a
Dexcom receiver or a smartphone or watch. In 2016, a previous
generation of monitors was recalled by the FDA because the
receiver's alarm didn't sound when the glucose reading was high or
low. But the company has since developed new technology, says CEO
Kevin Sayer.
The new monitor uses some finger pricking, says Mr. Sayer,
because "we've not seen anything sitting outside the body that
delivers the accuracy that patients require."
In a paper published earlier this year, Sunghoon Jang, chair of
the department of computer engineering tech at NY City College of
Technology at CUNY, surveyed a dozen emerging optical or
electrochemical technologies that target both blood and other
bodily fluids, including a contact lens that changes color
depending on the level of glucose present in tears. But none of
these techniques are commercially available, Dr. Jang says, showing
how complicated it can be to develop reliable and affordable
alternatives to more invasive ways of measuring glucose, which also
continue to improve.
Tracking Blood Pressure
Researchers have long tried to improve on the traditional arm
cuff to measure high blood pressure, which causes heart attacks and
strokes.
By 2020, three billion people will have smartphones, "and a lot
of people in this world have high blood pressure and don't know
it," says Ramakrishna Mukkamala, a professor of electrical and
computer engineering at Michigan State University.
Recently, a group he led created a way to take blood pressure
with a phone, using the same principle as the blood-pressure cuff,
which varies pressure on the arm. In a study published in March,
the group used a modified smartphone case with two sensors, one
that measured blood volume and one that measured applied pressure.
Users steadily pressed their fingertips against the case to get a
reading. The data was transmitted via Bluetooth to an app, which
calculated blood pressure and displayed it.
In September, however, a proof-of-concept study done by Dr.
Mukkamala and another set of authors showed that the same
finger-pressing method can be applied to optical and force sensors
that are already built into some phones -- one sensor for taking
selfies and one for displaying a 3-D touch feature.
The group has developed an iPhone app that guides fingertip
placement and calculates blood pressure. Comparing the results
against a traditional blood-pressure cuff, the app was less
accurate than the arm cuff. But Dr. Mukkamala says it was
comparable to a finger cuff, a device that's been cleared by the
FDA for measuring arm blood pressure but used primarily so far in
research. Dr. Mukkamala hopes to market the phone technology,
though he says it needs more work before it can be approved.
Another group is working on ways to test smartwatches that
monitor blood pressure. At the National Institute of Standards and
Technology, the Physical Measurement Laboratory is working with
Tufts University's School of Medicine to build a fake arm that
reproduces the mechanical properties of blood pulsing through an
artery and surrounded by human tissue. The arm could then be used
to test new blood-pressure monitors that would be worn like a
watch. NIST and Tufts expect to test optical sensors on the fake
arm that block specific frequencies or colors of light. As the
pressure changes, the color of light that is blocked also
changes.
Ms. Gage is a writer in San Jose, Calif. Email her at
reports@wsj.com.
(END) Dow Jones Newswires
September 16, 2018 22:20 ET (02:20 GMT)
Copyright (c) 2018 Dow Jones & Company, Inc.
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