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 The app in question, Instant Blood Pressure from AuraLife, was
designed to estimate blood pressure by placing the top edge of a
smartphone on the left side of the chest and holding the right index
finger over the camera on the device.
But approximately four out of every five people with hypertension
got inaccurate readings from the app that suggested their blood
pressure was in a normal range when it was actually high, the study
found.
“If Instant Blood Pressure worked, it would be a revolutionary new
technology that would allow for low-cost screening and management of
hypertension among smartphone users,” said lead study author Dr.
Timothy Plante of Johns Hopkins University in Baltimore.
“That it doesn’t use a cuff is neat as folks don’t generally like
carrying around a bulky blood pressure monitor,” Plante added by
email. “Inaccurate measurements for high or low readings are
concerning, however. Hypertension is known as the silent killer as
it has an asymptomatic course that leads to serious conditions like
heart disease, kidney disease, and stroke.”
At least 148,000 copies of the app were sold for $4.99 from June
2014 to July 2015, Plante and colleagues estimate in JAMA Internal
Medicine.
To test how well the app worked, the research team used the same
standards new blood pressure cuffs must meet to win U.S. regulatory
approval for use in doctors’ offices.
They enlisted 85 volunteers, more than half with a diagnosis of
hypertension and nearly all on medications for the condition.
Researchers checked blood pressure twice with the app, following the
instructions provided by the developer, and then compared the
average result from those two readings to a separate measurement
from a traditional blood pressure cuff.
Healthy people have a systolic blood pressure, the measurement when
the heart beats, of less than 120 mmHg, and diastolic pressure, when
the heart rests, of less than 80 mmHg. Blood pressure above 140 mmHg
systolic or 90 mmHg diastolic are considered hypertension.
The average differences between the app results and the traditional
cuff were 12.4 mmHg for systolic blood pressure and 10.1 mmHg for
diastolic blood pressure.
Generally, the app overestimated low blood pressure and
underestimated hypertension.
It’s hard to imagine any mobile app to measure blood pressure
without a hardware component that does the job of a cuff, said Dr.
Beverly Green, a researcher at Group Health Research Institute in
Seattle who wasn’t involved in the study.
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“I am not an engineer, but from what I understand, you need a cuff
(the thing that wraps around your arm and is pumped up) preferably
on the upper arm, to get an accurate BP,” Green said by email.
“The cuff compresses the arteries and measures the amount of
pressure the heart needs to get blood out to the arteries and the
pressure of the arteries when the heart is relaxed,” Green added.
The app was available in both Apple’s App Store and Google Play.
Even though it’s no longer sold, it’s possible some users still have
it on their phones. Apple confirmed the app was rejected, while
Google declined to comment.
Ryan Archdeacon, CEO and co-founder of AuraLife, told Reuters Health
by email that several issues with the study “render it invalid.”
Among these, multiple updates to the app during the study period and
afterward improved the accuracy of readings by 30 percent, according
to Archdeacon.
Moreover, the app was not designed to measure blood pressure above
158 mmHg systolic or 99 mmHg diastolic, he said. “Instant Blood
Pressure is not a medical device and is not intended to diagnose
disease, including hypertension,” Archdeacon said.
Apps have potential to help more than 1 billion patients with
hypertension worldwide manage their condition, though the findings
highlight the pitfalls of consumers using a nascent technology, said
Nilay Kumar, a researcher at Harvard University who wasn’t involved
in the study.
“While the promise of mobile health in revolutionizing hypertension
treatment is enormous, BP measurement using a smartphone is still in
its developmental stages,” Kumar said by email.
SOURCE: http://bit.ly/21HSUz5 JAMA Internal Medicine, online March
2, 2016.
(This version of the story corrects journal name in paragraph 6)
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