Comparison of electrochemical skin conductance and vibration perception threshold measurement in the detection of early diabetic neuropathy

Abstract

The early diagnosis of diabetic peripheral neuropathy (DPN) is challenging. Sudomotor dysfunction is one of the earliest detectable abnormalities in DPN. The present study aimed to determine the diagnostic performance of the electrochemical skin conductance (ESC) test in detecting early DPN, compared with the vibration perception threshold (VPT) test and diabetic neuropathy symptom (DNS) score, using the modified neuropathy disability score (NDS) as the reference standard. Five hundred and twenty-three patients with type 2 diabetes underwent an NDS-based clinical assessment for neuropathy. Participants were classified into the DPN and non-DPN groups based on the NDS (≥ 6). Both groups were evaluated further using the DNS, and VPT and ESC testing. A receiver-operator characteristic (ROC) curve analysis was performed to compare the efficacy of ESC measurements with those of DNS and VPT testing in detecting DPN. The DPN group (n = 110, 21%) had significantly higher HbA1c levels and longer diabetes durations compared with the non-DPN group (n = 413). The sensitivity of feet ESC < 60 μS, VPT testing, and DNS in detecting DPN were 85%, 72%, and 52%, respectively. The specificity of feet ESC, VPT, and DNS in detecting DPN were 85%, 90% and 60% respectively. The areas under the curves of the ROC plots for feet ESC, VPT testing, and DNS were 0.88, 0.84, and 0.6, respectively. A significant inverse linear relationship was noted between VPT and feet ESC (r = -0.45, p = <0.0001). The odds ratios for having DPN, based on the mean feet ESC testing < 60 μS, VPT testing > 15 V, and DNS ≥ 1, were 16.4, 10.9 and 1.8, respectively. ESC measurement is an objective and sensitive technique for the early detection of DPN. Feet ESC measurement was superior to VPT testing for identifying patients with early DPN.

The diagnostic usefulness of the combined COMPASS 31 questionnaire and electrochemical skin conductance for diabetic cardiovascular autonomic neuropathy and diabetic polyneuropathy

“…With regard to sudomotor assessment, we found that hands and feet ESC were lower in participants with CAN and DPN and were significantly related to all cardiovascular tests (in particular with deep breathing test: P < .0001) and the autonomic score, to the scores of neuropathic symptoms and signs, and to VPT, but not to thermal thresholds. These findings confirm previous observations of correlations of hands and feet ESC with clinical neuropathy scores (ie, NIS‐LL, UENS and MNSI, NDS and NSS, TCNS), deep breathing, Valsalva test, CARTs‐based autonomic score, VPT, and thermal thresholds, with the lowest significance for the latter . In the current study, feet ESC showed a fair diagnostic accuracy for CAN, in particular for confirmed CAN with an AUC of 0.92, while the abnormality of hands or feet ESC had the best sensitivity for confirmed CAN (83%) and the best specificity for DPN (67%).…”

“…The only relationship between ESC and clinical variables was that of mean ESC feet with triglycerides (rho = −0.273, P = .0065). In the analysis of covariance after adjustment for triglycerides, the significant differences in mean ESC feet between the groups with and without CAN and with and without 13,14 Valsalva test, 13 CARTs-based autonomic score, 14 VPT, 14,20,21,41 and thermal thresholds, with the lowest significance for the latter. 13 In the current study, feet ESC showed a fair diagnostic accuracy for CAN, in particular for confirmed CAN with an AUC of 0.92, while the abnormality of hands or feet ESC had the best sensitivity for confirmed CAN (83%) and the best specificity for DPN (67%).…”

“…11,15,16 The question of whether reduced ESC is the consequence of sudomotor fiber loss, reduced numbers or volume of sweat glands or sweat gland dysfunction 11,15 remains open. Moreover, when considering studies attempting to validate ESC measurement for the diagnosis of diabetic neuropathy, while values of sensitivity from 20% to 97% and specificity from 55% to 96% have been reported for DPN, 13,14,[17][18][19][20][21][22][23][24] data on diagnostic performance of ESC for CAN are limited, 14,25,26 and characterized by various diagnostic modalities for the number of CARTs used (from 2 to 4), an inconsistent use of age-related normative values for CARTs, and the substitution of feet or hands ESC measures for a scoring measure called CAN risk score based on both ESC results and clinical parameters 25,26 (Table 1). The study was performed in accordance with the ethical standards of the Declaration of Helsinki as revised in 2013 and was approved by the Ethics Committee of the University Hospital of Rome Tor Vergata.…”

New Perspective in Diabetic Neuropathy: From the Periphery to the Brain, a Call for Early Detection, and Precision Medicine

“…A recent large cross sectional study found ESC as measured by Sudoscan to be the most sensitive measure (Area under receiveroperator characteristic curve plot 0.88) for the early detection of DPN in comparison to VPT and clinical assessment (85). Additionally, it has a similar diagnostic utility as skin biopsy with IENFD measurement and it correlates with other measures such as clinical neuropathy scoring systems, QST, autonomic function testing and NCS parameters (82)(83)(84)(85)(86). However, a recent systematic review concluded that there was insufficient evidence to support that Sudoscan as a measure of sensory nerve fiber function, listing conflicts of interests, inconsistent normative values and insufficient sensitivity and specificity from pooled data-sets (87).…”

“…It is quick and easy to perform and has a sensitivity ranging between 70 and 87.5%, and specificity 76.2-92%, to detect DPN (82)(83)(84). A recent large cross sectional study found ESC as measured by Sudoscan to be the most sensitive measure (Area under receiveroperator characteristic curve plot 0.88) for the early detection of DPN in comparison to VPT and clinical assessment (85). Additionally, it has a similar diagnostic utility as skin biopsy with IENFD measurement and it correlates with other measures such as clinical neuropathy scoring systems, QST, autonomic function testing and NCS parameters (82)(83)(84)(85)(86).…”