System for Prediction of Recurrent DFU
because of participants becoming lost to follow-up.
Per protocol, the percentage of participants using the
system .3 days/week improves to 94.6%, with mean
adherence increasing to 5.5 days/week.
Nearly all participants (98.4%) were able to set up
and use the device at home without assistance. When
asked how easy the study device was to use on a scale
of 1 (very hard) to 4 (easy), 51 of 58 respondents (88%)
reported an ease of use of 4. No device-related adverse
events were reported during the study. The most
commonly noted adverse event was DFU recurrence.
CONCLUSIONS
W
e completed a multicenter evaluation of a
novel remote temperature-monitoring system to
characterize its predictive accuracy and usability. Our
results suggest that plantar temperature asymmetry
was highly predictive of impending DFU. In addition,
we examined different temperature asymmetry
thresholds and their impact on prediction sensitivity
and specificity, which represents a novel and previously
uncharacterized aspect of temperature monitoring of
the diabetic foot.
Using an asymmetry threshold of 2.22°C, the standard
threshold used in previous studies (15–17), the mat
was able to detect 97% of nontraumatic DFU; 5
weeks before they presented to the participant and/or
clinician. These data are consistent with and extend
the work of previous researchers. Additionally, the data
support clinical practice guidelines that emphasize
incorporating daily thermometry into standard
preventative care (15–17,19–21,24) .
The proportion of participants who developed a DFU
during this investigation is higher than previous studies
with similar enrollment criteria (15,16). However, it is
difficult to make a direct comparison because prior
studies did not characterize the duration between
when a participant healed from their most recent DFU
episode and when they were enrolled. This is known
to be a significant confounder (1,5–9) . We note a median
duration of 2.9 months from previous closure among
our participants, which potentially explains the high
observed incidence in part.
Despite the common impression that in-home
foot-temperature monitoring is unrealistic for this
population, daily adherence was encouraging, with
86% of the cohort averaging at least three uses per
week per an ITT analysis. Although this is the first
study to objectively examine longitudinal adherence
of which we are aware, it has been previously
demonstrated that patients with diabetes are poorly
adherent to therapeutic interventions, including
prescribed pressure-offloading strategies (25,26) . The
strong adherence could be because of the automation
and connectivity designed into the study device, which
enables continuous surveillance of adherence and
re-engagement when necessary, and the simplicity
of the mat form factor, which is supported by 88% of
respondents reporting it to be“easy”to use. Despite this
success, it is important to note that losses to follow-
up were observed, suggesting the system may not be
uniformly adopted by all patients.
High adherence may enable reductions in DFU
incidence beyond the 70% previously demonstrated
(15–17)
. Of the three randomized controlled trials that
evaluated temperature-guided avoidance therapy,
one paper (16) characterized the impact of poor
adherence on prevention. They noted four of the five
participants that ulcerated in the treatment group were
nonadherent to the prescribed monitoring regimen. It
is therefore conceivable that improved adherence may
result in larger reductions in incidence.
In addition, one potential benefit of the system
suggested by these data but not yet investigated is the
Current Pedorthics | September/October 2019
51