Patients' adherence to customised diabetic insoles as objectively assessed by a temperature sensor
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Abstract
Background and aims: Customized diabetic insoles reduce the mechanical
stress by re-distributing pressure to the plantar tissue. Thus, customized
diabetic insoles are an effective means to prevent the reoccurrence of
neuropathic diabetic foot ulcerations. However, the efficacy of these insoles
is highly dependent on patients’ adherence. By recommendation,
patients should wear their customized diabetic insoles as much as possible
for the prevention of diabetic foot problems. However, adherence data
often rely on self-report since objective parameters are not available. The
aim of this study was to objectively assess patients’ adherence with a
temperature sensor directly incorporated into their insoles.
Materials and methods: In a pilot study, the cut-off value for optimal
temperature was determined that differentiates between wearing and not
wearing footwear. For this purpose, a ROC analysis was conducted that
yielded an area under the curve of .996 (p<.0001). A cut-off value of
25°Celsius was determined that achieved a sensitivity of 95.3%, a specificity
of 99.8%, a positive predictive value of 98.7%, and a negative predictive
value of 99.2%. In the main study, temperature sensors were incorporated
into the specialized diabetic insoles of 26 patients with type-2-diabetes and
diabetic foot syndrome (age: 67.5±10.8 yrs.; 35% female; BMI: 30.3±
4.7 kg/m2
; diabetes duration: 10.4±6.8 yrs.; HbA1c: 7.7±0.6%).
Results: On average, data from 133.5 days per patient could be analysed.
Patients wore their diabetic footwear (temperature>25°C) on an average
(median) of 3.4 hours per day (inter-quartile-range (IQR): 0.5 - 6.9 hours/
per day). On an average (median) of 51% of days, patients did not wear
their diabetic footwear (IQR: 16.9 - 81.8%).
Conclusion: Wearing time of diabetic insoles and other specialized diabetic
footwear can be objectively and validly assessed by temperature
sensors. This study offers objective data regarding patients’ adherence
to their customized diabetic insoles. Nearly every second day, patients
did not wear their insoles at all. Results of this study indicate that the
utilization of specialized diabetic footwear is suboptimal in order to prevent
re-ulcerations and other diabetes foot problems. Future studies
should examine how the adherence of patients with a high risk for foot
ulcerations can be enhanced, e.g. by patient education or technological
assistance or reminders