A trial of proficiency of nerve conduction: greater standardization still needed

Abstract

Introduction: The aim of this study was to test the proficiency (accuracy among evaluators) of measured attributes of nerve conduction (NC).

Methods: Expert clinical neurophysiologists, without instruction or consensus development, from 4 different medical centers, independently assessed 8 attributes of NC in 24 patients with diabetes mellitus (DM) on consecutive days.

Results: No significant intraobserver differences between days 1 and 2 were found, but significant interobserver differences were seen. Use of standard reference values did not correct for these observed differences.

Conclusions: Interobserver variability was attributed to differences in performance of NC. It was of sufficient magnitude that it is of concern for the conduct of therapeutic trials. To deal with interrater variability in therapeutic trials, the same electromyographers should perform all NC assessments of individual patients or, preferably, NC procedures should be more standardized. A further trial is needed to test whether such standardization would eliminate interobserver variability.

Keywords: clinical trial; diabetic sensorimotor polyneuropathy; nerve conduction; proficiency; standard reference value.

FIGURE 1

The physical arrangement used to assess attributes of nerve conduction in the Cl vs. NPhys Trial 3, allowing masked examination of 24 patients with diabetes on 2 separate days. Curtained examination cubicles for NC assessment were at the periphery of the ballroom, which permitted lower limbs of the patients to be introduced for examination without the examiners being able to identify patients by their physical appearance. This setup allowed examiners to explain what was being done to each patient. It also allowed patients to report on excessive symptoms or reactions to the tests being given while not revealing their identity or disease condition.