The Rate of Decline in Small Fibre Function Assessed Using Axon Reflex-Mediated Neurogenic Vasodilatation and the Importance of Age Related Centile Values to Improve the Detection of Clinical NeuropathyReportar como inadecuado




The Rate of Decline in Small Fibre Function Assessed Using Axon Reflex-Mediated Neurogenic Vasodilatation and the Importance of Age Related Centile Values to Improve the Detection of Clinical Neuropathy - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Background

The LDIflare technique LDIflare is a simple non-invasive test of small fibre function in dorsal foot skin involving skin heating and measuring the size of the resulting axon reflex-mediated vasodilator flare response using a laser Doppler imager LDI. This study establishes age-related normative reference ranges for the test and determines the rate of decline in small fibre function per decade. Additionally, the potential value of using age related centiles rather than Receiver Operator Curves ROC was explored by comparison of the sensitivity and specificity of each analytic technique in identifying clinical neuropathy.

Methods

LDIflare areas were assessed in 94 healthy controls and 66 individuals with diabetes with DN+, n = 31 and without clinical neuropathy DN-, n = 35; neuropathy defined as a Neuropathy Disability Score ≥3. The age specific 5th centile values were used as the ‘cut-offs’ for the diagnosis of neuropathy from which sensitivity and specificity were calculated.

Results

There was a significant age dependant decrease in LDIflare size r = −0.42, p<0.0001 with no significant gender differences. The LDIflare size reduced 0.56 cm2 per decade which gives a percentage reduction of approximately 5.5% per decade. Using the normative 5th centiles as the cut-offs, the technique had a sensitivity of 77%, specificity of 90%, positive predictive value of 82% and negative predictive value of 87%.The ROC analysis gave a threshold of <3.66 cm2 for the cut-off, resulting in a sensitivity of 75%, specificity of 85%, positive predictive value of 74% and negative predictive value of 86%.

Conclusions

There is an age dependent decrease in small fibre function in the foot of 5.5% per decade. Both analytic techniques demonstrate good sensitivity and specificity for detecting clinical neuropathy but the technique based on age centiles offers better diagnostic accuracy and is therefore proposed as the method of choice.



Autor: Prashanth R. J. Vas, Gerry Rayman

Fuente: http://plos.srce.hr/



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