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 Diabetic foot ulcers typically develop on the bottom of the big toe
or the ball of the foot, often when people wear ill-fitting shoes.
Patients with diabetes frequently have nerve damage that limits
their ability to feel pain, and as a result they don’t notice
developing ulcers.
For the study, researchers tested a so-called smart mat designed to
use variations in temperature at different points on the foot as a
predictor of recurring foot ulcers in 129 patients who had this
problem before. Skin temperature typically increases as ulcers
develop.
When the study team tested for variations of 2.22 degrees Celsius
(about 4 degrees Fahrenheit), they found the smart mat correctly
identified 97 percent of foot ulcers observed by clinicians. But it
also had a “false positive” rate of 57 percent, meaning clinicians
didn’t find ulcers identified by the mat.
With a larger temperature variation of 3.20 degrees Celsius (about
5.75 degrees Fahrenheit), the false positive rate dropped to 32
percent, but the proportion of correctly identified foot ulcers also
declined to 70 percent, researchers report in Diabetes Care.
“If we look at this technology as a risk stratification tool with
high feasibility to be used at home on daily basis, it could be
hugely beneficial to target those who are truly at risk,” said
senior study author Dr. Bijan Najafi, a researcher at Baylor College
of Medicine in Houston.
“I don’t think the point is having a system with no false-alarm,”
Najafi said by email.
The device in the study was developed by Podimetrics Inc. in
Somerville, Massachusetts, and it’s approved for sale in the U.S.
for the periodic evaluation of temperature variations in the soles
of the feet for signs of inflammation. Podimetrics sponsored the
study of the mat for predicting diabetic foot ulcers.
In the current experiment, patients used the mat in much the same
way they might use a common bathroom scale. Every day, they stepped
on it and waited 20 seconds while it measured temperatures at
different points on the soles of the feet, then the device
wirelessly transmitted the temperature data to servers managed by
Podimetrics. The data were saved and analyzed for variations in foot
temperature that might signal developing ulcers.
In total, the trial ran 34 weeks, and 37 participants developed 53
foot ulcers during the study period.
For both of the temperature variation settings tested in the study,
the mat correctly identified developing ulcers an average of 37 days
before they were detected by a doctor.
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That lead time might help patients schedule clinic visits and get
treatment for ulcers sooner, when they’re easier to treat and less
likely to lead to serious complications, Najafi said.
The study wasn’t designed to determine whether the mat actually
reduced the development of ulcers or curbed costs to treat these
ulcers, the authors note. Researchers only followed patients for 60
days, and it’s possible the rate of false positives or accurately
identified ulcers might look different over a longer period of time.
In addition, the study only included patients with a history of
diabetic foot ulcers, and the results might be different for people
with diabetes who have never had this problem before, the authors
point out.
While the high rate of false positives in the study suggests that
the device still needs more testing and refinement, the technology
holds a lot of potential to aid patients who currently have a high
risk of infection and amputation because their developing ulcers go
undetected, said Dr. David Armstrong, director of the Southern
Arizona Limb Salvage Alliance at the University of Arizona College
of Medicine in Tucson.
“What’s really attractive about this technology is that it is
probably going to get smarter,” Armstrong, who wasn’t involved in
the study, said by email. “This technology is probably going to
personalize a heat signature for every patient and identify a hot
spot for each patient.”
SOURCE: http://bit.ly/2rAPZz6 Diabetes Care, April 29, 2017.
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