Screening patients at risk for diabetic foot ulceration: a comparison between measurement of vibration perception threshold and 10-g monofilament test

Abstract

The aim is to compare the frequency of increased vibration perception threshold (VPT) with abnormal 10-g Semmes-Weinstein monofilament (SWF) testing in a non-selected diabetic population, and to assess the agreement between these two screening methods. VPT was measured using a neurothesiometer at the pulp of the hallux and 10-g SWF was applied on three plantar sites on each foot according to the guidelines of the International Working Group on the Diabetic Foot, in 400 consecutive diabetic patients. VPT was considered as abnormal if ≥25 V and SWF was considered as abnormal if the patient was unable to feel ≥2 applications at a single site. Both tests were normal in 240 patients (60%) and both abnormal in 78. In 21 patients, only SWF was abnormal whereas only VPT was abnormal in 61. As a whole, 160 patients (40%) were considered at risk for foot ulceration by VPT and/or SWF. Agreement between the two screening methods was only moderate with a kappa coefficient of 0·52 (95% CI: 0·43-0·60). Using VPT as a predictor for foot ulceration, the number of patients at risk is much higher than identified by SWF. This discrepancy might have potential effects on costs and prevention policies.

Keywords: Foot ulcer; Monofilament; Screening; Vibration perception threshold.