The Concurrent Validity, Test-Retest Reliability and Usability of a New Foot Temperature Monitoring System for Persons with Diabetes at High Risk of Foot Ulceration

At-home foot temperature monitoring may be useful in the early recognition of imminent foot ulcers that occur through biomechanical loading in people with diabetes. We assessed the concurrent validity, test-retest reliability, and usability of a new plantar foot temperature monitoring device in 50 people with diabetes and peripheral neuropathy. We compared plantar foot temperature measurements with a platform system that consists of embedded temperature sensors with those from a handheld infrared thermometer that was used as a reference. Repeated platform assessments were compared for test-retest reliability. Usability was assessed in 15 participants who used both devices daily for two weeks at home, after which they completed a questionnaire. Agreement between devices was excellent for the metatarsal heads and heel (ICCs >= 0.98, LOA: -0.89 degrees C; 1.16 degrees C) and hallux and lateral midfoot (0.93 <= ICC <= 0.96, LOA: -2.87 degrees C; 2.2 degrees C), good for digits 2-5 (0.75 <= ICC <= 0.88, LOA: -5.04 degrees C; 2.76 degrees C), and poor for the medial midfoot (ICC = 0.19, LOA: -8.21 degrees C; -0.05 degrees C). Test-retest reliability was high (ICC = 0.99, LOA: -0.59 degrees C; 1.35 degrees C). Participants scored between 3.8 and 4.3 on a 5-point Likert scale for willingness to measure, ease of use, measurement comfort, and duration. In conclusion, the platform shows good concurrent validity in foot regions where most ulcers occur, good test-retest reliability, and good usability for measuring plantar foot temperature. Further research should assess the clinical validity of the platform to help prevent plantar diabetic foot ulcers.