Innovative Medical Technology

Neurotron, Incorporated

   Innovative Medical Technology

                 Established 1981

Omitted, Statistically Invalid, and Fraudulent Publications

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Omitted Publications

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Averaging Measures

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Reliability

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Change Between Repeated Measures

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Coefficient of Variation

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Prospective Evaluation

(dot)  Agreement (Concordance) of Data Evaluation
(dot)  References

 

Omitted Publications

Prescription medical devices are accompanied by instructions or guidelines for their safe and effective use. Any deviations in conducting the automated sNCT procedure or interpreting its measures may result in erroneous and invalid diagnostic information.  None of the publications listed in the comprehensive bibliography deviated significantly from these Manufacturers Recommended Guidelines in their application and analysis of sNCT/CPT studies. The publications listed below, however, were omitted from the bibliography because the authors failed to follow the procedures established for the proper analysis of the test data. The authors were notified about the errors in their methodologies and Letters to the Editor were published exposing the errors and their effect on the articles’ conclusions. However, unlike authors of other papers who had been informed of similar problems, the authors of these three publications never published corrections to their papers.  Note that publications below averaged both hyperesthetic and hypoesthetic Current Perception Threshold (CPT) measures.  Additional information regarding this type of statistical error is provided below.

1. Franzblau, A., Werner, R.A., Johnston, E., Torrey, S. Evaluation of Current Perception Threshold Testing as a Screening Procedure for Carpal Tunnel Syndrome among Industrial Workers. Journal of Occupational Medicine, Volume 36(9):1015-1021, 1994. [Note: In addition to the methodological errors in this publication, Dr. Franzblau, the principle author of this publication, testified in a Washington State hearing that subsequent to this publication he changed his definition of what constituted Carpal Tunnel Syndrome (CTS).] See letter to editor Journal of Occupational and Environmental Medicine, Volume 37 (7) 790-793, (July 1995).

2. Vinik, A.I., Suwanwalaikorn, S., Stansberry, K.B., Holland, M.T., McNitt, P.M., Colen, L.E. Quantitative Measurement of Cutaneous Perception in Diabetic Neuropathy. Muscle & Nerve, Volume 18:574-584, 1995.

3. Tack, C.J.J., Netten, P.M., Sheepers, M.H., Meijer, J.W.G., Smits, P., Lutterman, J. Comparison of clinical examination, current and vibratory perception threshold in diabetic neuropathy. Netherlands Journal of Medicine, Volume 44:41-49, 1994.

4. Park R., Wallace, M.S., Schulteis, G, Relative sensitivity to alfentanil and reliability of current perception threshold vs von Frey tactile stimulation and thermal sensory testing. Journal of the Peripheral Nervous System, Volume 6:232-240, 2001.

5. Shimoda, O., Ikuta, Y. The Current Perception Thresholds vary between horizontal and 70 degree tilt-up positions. Anesthesia and Analgesia, Volume 91:398-402, 2000. See: Chado, H.N., Related letter to editor Anesthesia & Analgesia, Volume 93:1079, 2001.
 

 

Fraudulent Publication
"AANEM Neurometer Technology Review"  American Association of Electrodiagnostic Medicine Technology Review: The Neurometer Current Perception Threshold (CPT). Muscle & Nerve, Vol. 22,:523-531, 1999.

 

This AANEM publication was excluded from the bibliography because it is fraudulent. It was falsely represented as a peer reviewed literature review from a committee of the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM), nee American Association of Electrodiagnostic Medicine (AAEM). Court documents, available upon request, establish the article was not peer reviewed, does not represent the consensus of a committee, was not written by 20 of the 21 authors listed, and did not follow its own criteria for evaluating literature. Additionally less than 19% of the cited papers in this opinion piece were actually reviewed. The author of the publication, George Baquis, MD, stated in sworn testimony that he had no knowledge of statistics although the review evaluation criteria required such knowledge.

 

 

 

 

Statistical Errors in the Evaluation of CPT Measures
 


Averaging Measures
Averaging together CPT measures, prevents the determination of the sensitivity of the test for conditions which may result in both hyperesthesia and hypoesthesia. 

Hyperestheia findings are similar to other biological measures, such as serum electrolytes, which also have a "U" shaped profile as a predictive factor for morbidity and mortality. Another example is blood pressure measurements. Although a patient’s systolic and diastolic measures can be averaged together, the resulting number has only minimal clinical utility. Blood pressure measures are commonly analyzed by examining the raw systolic and diastolic measures and comparing them to established upper and lower ranges of healthy measures. A third example is body temperatures. If a patient had a body temperature of 97.1°F at 10:00am, and had a body temperature of 101.1°F at 2:00pm, then it is without question that the patient’s temperature measures indicated an abnormality.  However, if the two temperature measures were averaged together before being evaluated, the resultant 98.6°F average measure would falsely indicate that no abnormality had been detected.

The CPT exam is capable of measuring the effects of conditions which can result in abnormally high (hypoesthetic) and abnormally low (hyperesthetic) current perception threshold levels. For example, studies have shown that diabetic patients suffer from both hyperesthesia and hypoesthesia. Suppose ten diabetic patients were tested with the 2000Hz stimulus on their great toes and their CPT measures were: 1) 24, 2) 999, 3) 236, 4) 844, 5) 35, 6) 745, 7) 588, 8) 126, 9) 84, 10) 999. The established range for healthy 2000Hz CPT measures on the great toe is 179 to 523. The average of all 10 CPT measures is 468, which would be within the healthy range. In reality, of course, nine out of the 10 patients had abnormal CPT measures. Patients 1, 5, 8 and 9 had hyperesthetic measures while patients 2, 4, 6, 7 and 10 had hypoesthetic or anesthetic measures. Only one patient in the group (#3) had a measure within the healthy range. For this reason it is generally not appropriate to analyze the sensitivity of CPT data by averaging patient measures.

Reliability
Reliability measures reproducibility, sensitivity and specificity. Concordance, discordance, sensitivity, specificity, and variability are all of words that have statistical definitions. These topics are discussed at this link.


Change Between Repeated Measures
When evaluating the change between repeated CPT determinations, it is generally appropriate to express the change as a percent change between serial evaluations. Expressing the data in terms of percent change provides a means of normalizing CPT measures between subjects. The percent change is calculated at each testing frequency (5Hz, 250Hz and 2000Hz). This percentage analysis also normalizes the different CPT frequency dependent measures for the comparison.  These topics are discussed at this link.

Coefficient of Variation
This is a valid measure of the reproducibility of repeated individual measures and has been reported in several publications. Typically this is expressed as the average of the percentage of the individual from their mean CPT. Various publications have evaluated repeated CPT measurements. The coefficient of variation for repeated measures averages approximately 6% at 2000 Hz, 12 % at 250 Hz and 16% at 5%. Each intra-subject automated double-blind CPT determination is confirmed to a p<0.006. (Studies which include coefficients of variation include references 1-4).  Additional information at this link.


Prospective Evaluation
This type of study is correlated with other medical measures over time and is more clinically oriented then the previous cited measures for example the following publications. (See references 5-7 below).

Agreement (Concordance) of Data Evaluation
This type of statistical evaluation is conducted to determine the rates of agreement (concordance) and disagreement (discordance) between the CPT studies repeated measures and the Neuval Database software evaluation of these measures. Publications which discuss the statistical basis of the Neuval Database software evaluation program include references 9-11 below.

Several factors can influence CPT measures including circadian rhythms age and sex. The normative range of CPT measures is large. From a clinical point of view, what is most significant is how consistent is the clinical evaluation (based on the Neuval Database software evaluation) of repeated measures. For example, if an individuals measures are “normal” today, will they be normal tomorrow and next year? At the 1997 meeting of the American Academy of Neurology, a group from the Mayo Clinic presented a study of the agreement (concordance) and disagreement (discordance) of repeated EMG (nerve conduction and electromyography (EMG) diagnoses from 200 patients (reference 8). This study reported a discordance rate of 40% (i.e., 40% of the time the follow-up EMG was not diagnostically consistent with the initial EMG). Concordance or agreement of repeated CPT measurements evaluated using the Neuval CPT evaluation is approximately 92%, while the discordance rate of the CPT evaluation is only 8%.

 

References:
 

1) Katims, J.J., Naviasky, E., Rendell, M.S., Ng, L.K.Y., Bleecker, M.L. Constant Current Sine Wave Transcutaneous Nerve Stimulation for the Evaluation of Peripheral Neuropathy. Archives of Physical Medicine and Rehabilitation, Volume 68:210-213, 1987.
 

2) Katims, J.J., Rouvelas, P., Sadler, B.T., Weseley, S.A. Current Perception Threshold: Reproducibility and Comparison with Nerve Conduction in Evaluation of Carpal Tunnel Syndrome. Transactions of the American Society of Artificial Internal Organs, Volume 35(3):280-284, 1989.
 

3) Masson, E.A., Veves, A., Fernando, D., Boulton, A.J.M. Current perception thresholds: a new, quick, and reproducible method for the assessment of peripheral neuropathy in diabetes mellitus. Diabetologia, Volume 32:724-728, 1989.
 

4) Parker G., Jr., Garzione, J., Testing the Reliability for Current Perception Threshold in the Physical Therapy Clinic. APTA Scientific Meeting and Exposition, Physical Therapy '97, San Diego, CA, 1997.
 

5) Avram M.W. Neurological Complications in Chronic Uremia Management. Morbidity and Mortality of Dialysis NIH Consensus Development Conference, pp. 123-128, November, 1993.
 

6) Avram M.W. Severe Neuropathy in Urban Dialysis Patients: Neurological Complications in Chronic Uremic Management. Contemporary Dialysis and Nephrology, Volume 15(4):22-23,34, April, 1994.
 

7) Weseley, S.A., Sadler, B., Katims, J.J. Current Perception: Preferred Test for Evaluation of Peripheral Nerve Integrity. Transactions of the American Society of Artificial Internal Organs, Volume 34(3):188-193, 1988.
 

8) Smith, B.E., Stevens, J.C., Caselli, R.J., Takata, J.H., Verheijde, J.L. and Weaver, A.L. Repeating the EMG can have a significant impact on diagnosis of neuromuscular disease. Neurology, Volume 48 (3), Suppl. 2,P01.083, page A52, 1997).

9) Weseley, S.A., Sadler, B., Katims, J.J. Current Perception: Preferred Test for Evaluation of Peripheral Nerve Integrity. Transactions of the American Society of Artificial Internal Organs, Volume 34(3):188-193, 1988.
 

10) Katims, J.J., Rouvelas, P., Sadler, B.T., Weseley, S.A. Current Perception Threshold: Reproducibility and Comparison with Nerve Conduction in Evaluation of Carpal Tunnel Syndrome. Transactions of the American Society of Artificial Internal Organs, Volume 35(3):280-284, 1989.
 

11) Katims, J.J., Patil, A.S., Rendell, M., Rouvelas, P., Sadler, B., Weseley, S.A., Bleecker, M.L. Current Perception Threshold Screening for Carpal Tunnel Syndrome. Archives of Environmental Health, Volume 46(4):207-212, 1991.

 

 

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rev 04/24/10