Proficiency of nerve conduction using standard methods and reference values (Cl. NPhys Trial 4).

INTRODUCTION: The Cl. NPhys Trial 3 showed that attributes of nerve conduction (NC) were without significant intraobserver differences, although there were significant interobserver differences. METHODS: Trial 4 tested whether use of written instructions and pretrial agreement on techniques and use of standard reference values, diagnostic percentile values, or broader categorization of abnormality could reduce significant interobserver disagreement and improve agreement among clinical neurophysiologists. RESULTS: The Trial 4 modifications markedly decreased, but did not eliminate, significant interobserver differences of measured attributes of NC. Use of standard reference values and defined percentile values of abnormality decreased interobserver disagreement and improved agreement of judgment of abnormality among evaluators. Therefore, the same clinical neurophysiologist should perform repeat NCs of therapeutic trial patients. CONCLUSIONS: Differences in interobserver judgment of abnormality decrease with use of common standard reference values and a defined percentile level of abnormality, providing a rationale for their use in therapeutic trials and medical practice.

"Unequivocally Abnormal" vs "Usual" Signs and Symptoms for Proficient Diagnosis of Diabetic Polyneuropathy: Cl vs N Phys Trial.

OBJECTIVE To repeat the Clinical vs Neurophysiology (Cl vs N Phys) trial using "unequivocally abnormal" signs and symptoms (Trial 2) compared with the earlier trial (Trial 1), which used "usual" signs and symptoms. DESIGN Standard and referenced nerve conduction abnormalities were used in both Trials 1 and 2 as the standard criterion indicative of diabetic sensorimotor polyneuropathy. Physician proficiency (accuracy among evaluators) was compared between Trials 1 and 2. SETTING Academic medical centers in Canada, Denmark, England, and the United States. PARTICIPANTS Thirteen expert neuromuscular physicians. One expert was replaced in Trial 2. RESULTS The marked overreporting, especially of signs, in Trial 1 was avoided in Trial 2. Reproducibility of diagnosis between days 1 and 2 was significantly (P = .005) better in Trial 2. The correlation of the following clinical scores with composite nerve conduction measures spanning the range of normality and abnormality was improved in Trial 2: pinprick sensation (P = .03), decreased reflexes (P = .06), touch-pressure sensation (P = .06), and the sum of symptoms (P = .06). CONCLUSIONS The simple pretrial decision to use unequivocally abnormal signs and symptoms-taking age, sex, and physical variables into account-in making clinical judgments for the diagnosis of diabetic sensorimotor polyneuropathy (Trial 2) improves physician proficiency compared with use of usual elicitation of signs and symptoms (Trial 1); both compare to confirmed nerve conduction abnormality.

Impaired glycemia and diabetic polyneuropathy: the OC IG Survey.

OBJECTIVE: To test whether diabetic polyneuropathies (DPNs), retinopathy, or nephropathy is more prevalent in subjects with impaired glycemia (IG) (abnormality of impaired fasting glucose [IFG], impaired glucose tolerance [IGT], or impaired HbA(1c) [IA1C]) than in healthy subjects (non-IG). RESEARCH DESIGN AND METHODS: Matched IG and non-IG volunteers were randomly identified from population-based diagnostic and laboratory registries, restudied, and reclassified as non-IG (n = 150), IG (n = 174), or new diabetes (n = 218). RESULTS: Frequency (%) of DPN in non-IG, IG, and new diabetes was 3 (2.0%), 3 (1.7%), and 17 (7.8%) narrowly defined (no other cause for polyneuropathy) and 19 (12.7%), 22 (12.6%), and 38 (17.4%) broadly defined. Mean and frequency distribution of composite scores of nerve conduction and quantitative sensation tests were not significantly different between IG and non-IG but were worse in new diabetes. Frequency of retinopathy and nephropathy was significantly increased only in new diabetes. In secondary analysis, small but significant increases in retinopathy and nephropathy were found in IGT, IFG, and IGT combined groups. CONCLUSIONS: In population studies of Olmsted County, Minnesota, inhabitants, prevalence of typical DPN, retinopathy, and nephropathy was significantly increased only in subjects with new diabetes-not in subjects with IG as defined by American Diabetes Association (ADA) criteria of abnormality of IFG, IGT, or IA1C. For atypical DPN, such an increase was not observed even in subjects with new diabetes. In medical practice, explanations other than IG should be sought for patients with atypical DPN (chronic idiopathic axonal polyneuropathy) who have IG.

Signs and symptoms versus nerve conduction studies to diagnose diabetic sensorimotor polyneuropathy: Cl vs. NPhys trial.

The purpose was to test whether physicians can validly and reproducibly diagnose diabetic sensorimotor polyneuropathy (DSPN). Twelve physicians assessed 24 patients with diabetes mellitus (DM) on consecutive days (576 examinations) with physical features and voice disguised. Results were compared to gold standard 75% group diagnosis (dx) and a nerve conduction score (Sigma5 NC nds). Masking of patients was achieved. Reproducibility measured by the kappa coefficient and compared to Sigma5 NC nd varied considerably among physicians: median and ranges: signs 0.8 (0.32-1.0); symptoms 0.79 (0.36-1.0), and diagnoses 0.47 (0.33-0.84), both low and high scores indicating poor performance. There was substantial agreement between 75% group dx and confirmed NC abnormality (abn). As compared to Sigma5 NC, individual physicians' clinical dx was excessively variable and frequently inaccurate. Study physician dx from signs and symptoms were excessively variable, often overestimating DSPN. Specific approaches to improving clinical proficiency should be tested.