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.
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
1. Arad, Y., et al., Beyond the monofilament for the insensate diabetic foot: a systematic review of randomized trials to prevent the occurrence of plantar foot ulcers in patients with diabetes. Diabetes Care, 2011. 34(4): p. 1041-6.
2. Chatzikosma, G., et al., Evaluation of sural nerve automated nerve conduction study in the diagnosis of peripheral neuropathy in patients with type 2 diabetes mellitus. Arch Med Sci, 2016. 12(2): p. 390-3.
3. Crawford, F., et al., A systematic review and individual patient data meta-analysis of prognostic factors for foot ulceration in people with diabetes: the international research collaboration for the prediction of diabetic foot ulcerations (PODUS). Health Technol Assess, 2015. 19(57): p. 1-210.
4. de Souza, R.J., A. de Souza, and M.D. Nagvekar, Nerve conduction studies in diabetics presymptomatic and symptomatic for diabetic polyneuropathy. J Diabetes Complications, 2015. 29(6): p. 811-7.
5. Dyck, P.J., et al., Assessing decreased sensation and increased sensory phenomena in diabetic polyneuropathies. Diabetes, 2013. 62(11): p. 3677-86.
6. Feng, Y., F.J. Schlosser, and B.E. Sumpio, The Semmes Weinstein monofilament examination is a significant predictor of the risk of foot ulceration and amputation in patients with diabetes mellitus. J Vasc Surg, 2011. 53(1): p. 220-226 e1-5.
7. Kong, X., et al., Utilization of nerve conduction studies for the diagnosis of polyneuropathy in patients with diabetes: a retrospective analysis of a large patient series. J Diabetes Sci Technol, 2008. 2(2): p. 268-74.
8. Muniz, E.C., et al., Neuropathic and ischemic changes of the foot in Brazilian patients with diabetes. Ostomy Wound Manage, 2003. 49(8): p. 60-70, 72-3.
9. Rayman, G., et al., The Ipswich Touch Test: a simple and novel method to identify inpatients with diabetes at risk of foot ulceration. Diabetes Care, 2011. 34(7): p. 1517-8.
10. Samuel, B.S. and S.J. Appel, Identifying early signs of peripheral neuropathy among patients with diabetes mellitus. Nurse Pract, 2016. 41(1).
11. Sharma, S., et al., The Ipswich Touch Test: a simple and novel method to screen patients with diabetes at home for increased risk of foot ulceration. Diabet Med, 2014. 31(9): p. 1100-3.