Faculty of Health Sciences, University of Southampton and Solent NHS Trust, Southampton, UK
Objective: There is a need to accurately identify neuropathy in people with type 2 diabetes, to help with risk stratification, and thus guide appropriate clinical management. Current guidelines by the National Institute for Health and Care Excellence (NICE) on the diabetic foot assessment are constructed around determining the risk of ulceration (NICE NG19 2015). The sensory neurological assessments however presents challenges as they are poorly standardised, rely on subjective responses, remain vulnerable to operator variability and are poorly sensitive at identifying early neuropathy. Therefore the recommended sensory assessments are not sensitive enough at detecting early neurological impairment, which further affects the effectiveness of early intervention strategies.
Aim: This study aimed to compare the extent of agreement in detecting neuropathy in participants with type 2 diabetes, between the recommended NICE 10g monofilament, against a portable nerve conduction device (NCstat ® DPNCheck; Neurometrix, Inc., Waltham, MA, USA).
Problem statement: The current NICE recommended sensory assessment methods are poorly able to identify early diabetic neuropathic impairment.
Methods: Recruitment: 28 adult participants between 18 - 65 years of age, with type 2 diabetes were recruited at Solent NHS Trust sites.
Ethical approval
The study was processed through the University of Southampton's Ethics and Research Governance Online (ERGO 13474), and ethical approval was obtained through the Integrated Research Application System (IRAS 170265), and Research Ethics Committee (17/LO/2033) and the local Health Research Authority.
Assessment of never function: The DPN-Check measures nerve conduction velocity of the sural nerve (meters per second) and amplitude (microvolts) following the procedure below, with normative values and a chart for interpretation. The whole nerve conduction procedure took on average 15 seconds to complete. The monofilament will be used to assess sensory neuropathy with scores out of 10.
Results: Cohen's κappa was run to determine the extent of agreement between the two instruments on whether 28 individuals with type 2 diabetes had neuropathy. There was poor agreement between the two instruments, κ = .329 (95% CI, 0.14 to 0.52), p = 0 .001. The 10g monofilament classified 19 participants as having no sensory deficit, and therefore at low risk of developing ulceration. The DPN-check classified 13 participants as having no sensory deficit. The 10g monofilament was unable to detect neuropathy in 24% of participants who showed nerve conduction abnormalities, and there was further disagreement in staging of the neuropathy between the two instruments.
Conclusion: The 10g monofilament demonstrated an impaired ability to detect neuropathy, and poorly agreed with an objective reference standard. This leaves the 10g monofilament underestimating ulceration risk; and poorly risk stratifies individuals with type 2 diabetes. Participants at higher risk status would be mis-classified and treated as lower risk, with limited access to more intensive management provided to higher risk individuals. The current health service guidelines suggest a wait for a change in the risk status to justify more intensive intervention. By this time it may be too late to implement effective strategies. The nerve conduction device (DPN-Check) has the potential to accurately determine an individual’s’ ulceration risk status in the early stages of diabetes, and guide timely management
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