Point-of-care sural nerve conduction could predict the presence of cardiovascular autonomic neuropathy in type 1 diabetes mellitus

Abstract

Aims: Assessment for cardiovascular autonomic neuropathy (CAN) in patients with type 1 diabetes mellitus remains time-consuming in the clinical setting. We aimed to examine the diagnostic performance of a portable point-of-care diagnostic tool (POCD) for assessing sural nerve conduction during the screening of CAN. Methods: Nerve amplitude (AMPPOCD) and conduction velocity (CVPOCD) were measured in a cross-sectional study including 198 asymptomatic patients with type 1 diabetes. CAN was diagnosed by the Ewing score and power spectral heart rate [low-frequency (LF) and high-frequency (HF) activity]. Diagnostic accuracy was determined by ROC curves. Results: CVPOCD and AMPPOCD showed positive correlations with LF and HF, and a negative correlation with age. Overall, AMPPOCD had an 81.7% accuracy in identifying CAN [AUC = 0.817 (95% CI 0.692–0.942)] with an AMPPOCD ≤6 μV showing 90% sensitivity and 73% specificity. In a stepwise binary logistic regression analysis, the model (R2: 0.297; P < 0.001) retained the duration of type 1 diabetes [β: 1.131 (95% CI: 1.051–1.216); P = 0.001) and A1c [β: 2.131 (95% CI: 1.060–4.283); P = 0.034) as significant predictors of CAN. The combination of AMPPOCD ≤6 μV + a type 1 diabetes duration of ≥8 years maximized the sensitivity, showing a diagnostic performance of 87% [AUC = 0.867 (95% CI 0.769–0.965)] with 90%, 76%, and 99%, sensitivity, specificity, and NPV, respectively. Adding A1c ≥ 7% to this model maintained accuracy [AUC = 0.867 (95% CI: 0.788–0.963) and NPV (99%), while increasing specificity to 84%. Conclusions: The combination of AMPPOCD with A1c and the duration of type 1 diabetes mellitus showed a good performance for the detection of asymptomatic CAN, making POCD an easy and rapid test for its routine screening in the clinical setting.