8/3/2019 Assessment of Diabetic Neuropathy

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Assessment of Diabetic Peripheral Neuropathy in Community Clinical Setting Using Automated NeS. Gozani, M.D., Ph.D. and X. Kong, Ph.D., Waltham, MA

INTRODUCTION

It is estimated that 13 million people in US have diabetes 1. Diabetic peripheralneuropathy (DPN) is a particularly debilitating complication of diabetes 2. It isestimated that about 60% of type I diabetics and 50% of type II diabetics have DPN,either symptomatic or asymptomatic. Nerve conduction studies (NCS) have a key rolein the assessment of DPN3. However, widespread use of NCS for DPN assessment

has been limited for logistical and economic reasons. Automated in-office NCS mayfacilitate assessment DPN in community clinical settings. The performance of the

NC-stat NCS system (NEUROMetrix, Inc, Waltham, MA) was evaluated in thisstudy. In particular, the following metrics were evaluated: Yield rate. Rate of NCS parameter abnormalities. DPN classification rate.

Correlation of NCS parameters with markers of diabetes severity.

METHODS

OVERVIEW

Automated NCS system (NC-stat, NEUROMetrix, Inc) was utilized in 26community clinics over 4 months.

Bilateral peroneal NCS were obtained for up to 60 diabetic patients per clinic.

First 1000 patients with diabetes and available sensory symptom score wereincluded in the analysis.

STUDY SUBJECT CHARACTERISTICS

Description Mean (Std) Description Percent

Age (year) 58.5 (11.2) Old than 65 year 39.1%Height (cm) 170.4 (10.8) Female 49.2%Weight (kg) 89.1 (15.4) Type II Diabetes 81.7%BMI (kg/m2) 30.7 (5.2)Ankle Temp (oC) 30.0 (1.5) HbA1c: < 6 17.8%

HbA1c: 68 58.2%Systolic BP (mmHg) 131.3 (15.9) HbA1c: 810 17.3%

Diastolic BP (mmHg) 75.3 (10.5) HbA1c: > 10 6.7%

SENSORY SYMPTOM SCORE

METHODS (Continued)

NERVE CONDUCTION STUDY PROCEDURE

Place pre-configured peroneal biosensor on foot. Connect NC-stat Monitor to biosensor. Perform nerve conduction study by NC-stat Monitor.

Download test for onCall report on DML, CMAP, FWL, and A-wave results.

NERVE CONDUCTION STUDY PARAMETERS

DML (Distal Motor Latency): onset latency of on-muscle compound actionpotential (CMAP).

CMAP Amplitude: CMAP peak to base amplitude. FWL (F-wave Latency): mean of individual latencies from each F-wave set.

Number of latencies is the minimum of 20 and number of F-waves detected in 40F-wave traces (not all F-wave traces will have F-wave).

A-wave: Presence of waveform component with consistent morphology and onsettime in more than 40% of F-wave traces.

All NCS parameters were determined automatically by NC-stat system. Latencyparameters (DML and FWL) were age, height, and ankle temperature adjusted beforecomparing with abnormal threshold values. Abnormal thresholds were the actual 5th

percentile (for DML and FWL) and 95 th percentile (for CMAP Amplitude) values of anon-diabetic reference population.

Illustration of the Nerve Conduction Study Parameter Definitions

RESULTS

YIELD RATE

Nerve conduction study results were obtained for 98.7% of nerves in this clinstudy.

RATE OF NCS PARAMETER ABNORMALITIESAbnormality threshold values were set at the actual 5th percentile (DML and Fand 95th percentile (CMAP Amplitude) values of a non-diabetic reference popula

DML CMAPAmp FWL A-wave0

10

20

30

40

50

60

70

%o

fNerveswithAb

normality

Rate of NCS Parameter Abnormalities for Individual Nerves.

DPN CLASSIFICATION RATE

Case Definition: Bilateral abnormalities of any NCS parameter at its 95 th speciThe case definition has a specificity of 97% based on non-diabetic reference data

Classification rate of DPN in diabetic patients using NC-stat system. DPNincreases with sensory symptom score. Zero score indicates asymptomatic.

Sensory Symptom Score 0 12 36 allClassification Rate 52.1% 61.8% 67.7% 61.9%

Classification rate of DPN in diabetic patients using NC-stat system. DPNincreases with diabetes disease duration (in years).

Diabetes Duration < 1 15 610 1120 >20 Classific ation Rate 42.4% 50.0% 61.5% 75.1% 82.7% 6

Classification rate of DPN in diabetic patients using NC-stat system. DPNincreases with HbA1c.

HbA1c < 6 68 810 > 10

Classification Rate 53.3% 60.3% 74.3% 73.9%

NC-stat System Overview

Disposable Biosensor NC-stat Monitor OnCall Report

with Docking Station

Sensory Symptom Score (derived from NTSS-6)

1. Do you experience a deep, aching, tightness, boring, pulling or squeezingpain in your feet or legs?2. Do you experience burning pain in your feet or legs?3. Do you experience a prickling or tingling feeling with or without an

asleep feeling in your feet or legs?

4. Do you experience asleep numbness, lost sensation, dead feeling like ananesthetic without prickling in your feet or legs?

5. Do you experience sharp, stabbing or shooting pain, electrical shock-likepain or surges of pain which lasts seconds to minutes in your feet or legs?

6. Do you experience unusual sensitivity or tenderness when your feet aretouched or are used in activities such as walking?

[Each affirmative answer counts as 1 unit]Sensory Symptom Score Distributions

0[asymptomatic]

12[intermediate]

36[advanced]

allmean (std)

23.4% 36.1% 40.5% 2.2 (1.9)

30 40 50 60 70

FWLA-wave

Time (ms)

Peroneal F-Wave Set

0 5 10

DML

CMAP Amplitude

Peroneal CMAP

Time (ms)