Clinical characteristics of the 64 healthy volunteers and of the 89 type 1 diabetes participants according to diabetic sensorimotor polyneuropathy status.

<p>Plus-minus values are means ± SD. [IQR] represents the interquartile range.</p>*<p>P values for categorical variables were calculated with the χ2 test, and ANOVA was used for continuous variables.</p>†<p>TCNS, Toronto clinical Neuropathy score. Scores of 0–5 are generally considered to represent low likelihood of DSP, 6–8 represents likelihood of mild neuropathy, 9–12 represent likelihood of moderate neuropathy, while 12–19 represent severe neuropathy.</p>‡<p>Axon-reflex mediated neurogenic vasodilatation by the laser doppler imaging flare method.</p

Box-And-Whisker Plots Demonstrating The Distribution Of LDI_FLARE Area In 64 Healthy Volunteers And 89 Type 1 Diabetes Subjects According To Neuropathy Status.

<p>Compared to the healthy volunteer group LDI_FLARE area was significantly smaller in subjects with type 1 diabetes without DSP (p = 0.006). Compared to subjects with type 1 diabetes controls without DSP, LDI_FLARE area was smaller in cases with DSP (p = 0.0.0002). As indicated in the figure, among controls the LDI_FLARE area was not different according to presence or absence of subclinical sural nerve impairment. Similarly, the LDI_FLARE area was similar among cases with DSP regardless of severity. The criteria for mild neuropathy were two or more abnormal nerve conduction parameters in the lower limb (sural and peroneal nerve distributions), and moderate and severe neuropathy were defined by four and five abnormal parameters, respectively. NCS, nerve conduction study. LDI_FLARE, laser doppler imaging flare. DSP, diabetic sensorimotor polyneuropathy.</p

Regression Analysis Of LDI_FLARE Area And Baseline Demographics.

*<p>The multivariate model included the variables that were significant in univariate analysis in either the healthy volunteer of type 1 diabetes cohorts. Direct measures of neuropathy – which included the TCNS and the nerve conduction studies – were not considered in the multivariate analysis.</p><p>HbA1c, glycated hemoglobin A1c.</p

Characteristics of 52 healthy volunteers and 136 subjects with type 1 diabetes.

<p>Data presented as mean ± sd and/or median[IQR], unless otherwise noted. P-values for comparison are from the ANOVA test (for continuous parametric variables), the Kruskal-Wallis test (for continuous non-parametric variables), or from logistic regression (for dichotomous variables).</p><p>DSP, diabetic sensory polyneuropathy; TCNS, Toronto clinical neuropathy score; HbA1c, glycated hemoglobin; LDL, low density lipoprotein; ACR, albumin-to-creatinine ratio from spot urine samples; eGFR, estimated glomerular filtration rate; LDI_FLARE, axon–reflex mediated neurogenic vasodilatation in response to cutaneous heating by the laser doppler imaging flare technique.</p><p>Characteristics of 52 healthy volunteers and 136 subjects with type 1 diabetes.</p

ROC curves for functional small fiber measures and the TCNS in the identification of clinical DSP in 136 Subjects with type 1 diabetes.

<p>Clinical DSP was defined as having a nerve conduction abnormality in both the sural sensory nerve and peroneal motor nerve, in addition to at least one clinical sign or symptom. AUCs for CDT, TCNS, HRV, and LDI were 0.863, 0.858, 0.788, and 0.745, respectively. The optimal threshold for CDT (*) was 25.1°C (83% sensitivity, 82% specificity).</p

Distribution of CDT values according to DSP case-control status in the 52 healthy volunteers and 136 subjects with type 1 diabetes.

<p>Horizontal bars represent the median for each group.</p

Intra Class Correlation coefficients for all T1DM participants (n = 26).

<p>ICC: Intra-class correlation coefficient (2, 1). Inter refers to inter-observer reproducibility, intra to intra-observer reproducibility. The manual protocol included manual image selection and manual image analysis. The semi-automated protocol included manual image selection and automated analysis. The fully-automated protocol included automated image selection and automated analysis. CNFL, corneal nerve fibre length. CNFD, corneal nerve fibre density. CNBD, corneal nerve branch density.</p><p>* Manual protocol ICC have been presented in a previous publication and are shown here for comparison.</p><p>† For the 13-member sub-population without DSP, inter-observer ICC for CNFL_{Fully-Automated} was 0.78(0.30,0.93) and intra-observer ICC for CNFL_{Fully-Automated} was 0.84(0.55,0.95). For the 13-member sub-population with DSP, the inter-observer ICC for CNFL_{Fully-Automated} was 0.65(0.05,0.89) and intra-observer ICC for CNFL_{Fully-Automated} was 0.72(0.31,0.90). Comparisons of these ICC were not statistically significant.</p><p>Intra Class Correlation coefficients for all T1DM participants (n = 26).</p

Reproducibility of <i>In Vivo</i> Corneal Confocal Microscopy Using an Automated Analysis Program for Detection of Diabetic Sensorimotor Polyneuropathy

<div><p>Objective</p><p><i>In vivo</i> Corneal Confocal Microscopy (IVCCM) is a validated, non-invasive test for diabetic sensorimotor polyneuropathy (DSP) detection, but its utility is limited by the image analysis time and expertise required. We aimed to determine the inter- and intra-observer reproducibility of a novel automated analysis program compared to manual analysis.</p><p>Methods</p><p>In a cross-sectional diagnostic study, 20 non-diabetes controls (mean age 41.4±17.3y, HbA1c 5.5±0.4%) and 26 participants with type 1 diabetes (42.8±16.9y, 8.0±1.9%) underwent two separate IVCCM examinations by one observer and a third by an independent observer. Along with nerve density and branch density, corneal nerve fibre length (CNFL) was obtained by manual analysis (CNFL_MANUAL), a protocol in which images were manually selected for automated analysis (CNFL_{SEMI-AUTOMATED}), and one in which selection and analysis were performed electronically (CNFL_{FULLY-AUTOMATED}). Reproducibility of each protocol was determined using intraclass correlation coefficients (ICC) and, as a secondary objective, the method of Bland and Altman was used to explore agreement between protocols.</p><p>Results</p><p>Mean CNFL_Manual was 16.7±4.0, 13.9±4.2 mm/mm² for non-diabetes controls and diabetes participants, while CNFL_{Semi-Automated} was 10.2±3.3, 8.6±3.0 mm/mm² and CNFL_{Fully-Automated} was 12.5±2.8, 10.9 ± 2.9 mm/mm². Inter-observer ICC and 95% confidence intervals (95%CI) were 0.73(0.56, 0.84), 0.75(0.59, 0.85), and 0.78(0.63, 0.87), respectively (p = NS for all comparisons). Intra-observer ICC and 95%CI were 0.72(0.55, 0.83), 0.74(0.57, 0.85), and 0.84(0.73, 0.91), respectively (p<0.05 for CNFL_{Fully-Automated} compared to others). The other IVCCM parameters had substantially lower ICC compared to those for CNFL. CNFL_{Semi-Automated} and CNFL_{Fully-Automated} underestimated CNFL_Manual by mean and 95%CI of 35.1(-4.5, 67.5)% and 21.0(-21.6, 46.1)%, respectively.</p><p>Conclusions</p><p>Despite an apparent measurement (underestimation) bias in comparison to the manual strategy of image analysis, fully-automated analysis preserves CNFL reproducibility. Future work must determine the diagnostic thresholds specific to the fully-automated measure of CNFL.</p></div

Agreement between CNFL_Manual and CNFL_{Fully-Automated}.

<p>In Panels A and B, the reference lines, from top to bottom, denote the 97.5th percentile, the mean, and the 2.5th percentile for the indicated differences.</p

Agreement between CNFL_Manual and CNFL_{Semi-Automated}.

<p>In Panels A and B, the reference lines, from top to bottom, denote the 97.5th percentile, the mean, and the 2.5th percentile for the indicated differences.</p