To determine normative values for nerve conduction studies among workers, we selected a subset of 326 workers from 955 subjects who participated in medical surveys in the workplace. The reference cohort was composed exclusively of active workers, in contrast to the typical convenience samples. Nerve conduction measures included bilateral median and ulnar sensory amplitude and latency (onset and peak). Workers with upper extremity symptoms, medical conditions that could adversely affect peripheral nerve function, low hand temperature, or highly repetitive jobs were excluded from the “normal” cohort. Linear regression models explained between 21% and 51% of the variance in nerve function, with covariates of age, sex, hand temperature, and anthropometric factors. The most robust models were fitted for sensory amplitudes in the median and ulnar nerves for dominant and nondominant hands. The median–ulnar difference was least sensitive to adjustment, indicating it is the best measure to use if corrections are not made to account for relevant covariates. A key point was that the magnitude of variance increased with age and anthropometric factors. These findings provide strong evidence that to improve diagnostic accuracy, electrodiagnostic testing should control for relevant covariates, particularly age, sex, hand temperature, and anthropometric factors. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:999–1005, 1998.

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Nerve conduction studies play an important role in clinical practice and research. Given their widespread use, reliability of tests merits careful attention. We assessed interexaminer and intraexaminer reliability of median and ulnar sensory nerve measures of amplitude, onset latency, and peak latency. In a two‐phase cross‐sectional study, two examiners tested 158 workers. Reliability was assessed with intraclass correlations (ICC) and kappa statistics. Median nerve measures were more reliable (ICC range, 0.76 to 0.92) than ulnar measures (ICC range, 0.22 to 0.85). Ulnar‐onset latencies had the worst reliability. The median‐ulnar peak latency difference was a particularly stable measure (ICC range, 0.79 to 0.92). The median‐ulnar peak latency difference had high interexaminer reliability (κ range, 0.71 to 0.79) for normal tests defined by cut points of 0.8 ms and 0.5 ms. Intraexaminer reliability was higher with the 0.8‐ms cut point (κ = 0.90 and κ = 0.85 for examiners 1 and 2, respectively). Rather than absolute cut points to describe normality, a more rational interpretation of results can be made with ordered categories or continuous measures. © 1999 John Wiley & Sons, Inc. Muscle Nerve 22: 1372–1379, 1999

Reliability of items on the Upper Extremity Questionnaire were generally good to excellent. Reports of symptom severity and interference with work were less stable. Demographic and work-related factors were not statistically significant in modeling the variation in reliability. Repeated use of the questionnaire with similar results suggests findings are applicable to a larger working population.

In order to identify functional status measures for epidemiological studies among workers with mild to moderate disorders of the neck and upper extremity, a literature search was conducted for the years 1966 to 2001. Inclusion criteria were: (1) relevance to neck and upper extremity; (2) assessment among workers; and (3) relevance to mild to moderate disorders. Of 13 instruments reviewed, six measures were tested among workers. The three best measures, depending on the purpose of research, included the standardised Nordic Musculoskeletal Questionnaire, the Upper Extremity Questionnaire, and the Neck and Upper Limb Instrument. Development of a functional protocol is regarded as a realistic enhancement for research of neck and upper extremity disorders in the workplace. For research and clinical practice, measures of functional status, sensitive enough to measure the subtle conditions in mild to moderate disorders, may provide prognostic information about the risk of developing musculoskeletal disorders in apparently healthy patients. Appropriate use of functional status questionnaires is imperative for a meaningful portrayal of health.