Covariates of human peripheral nerve function: I. Nerve conduction velocity and amplitude.

A systematic investigation of covariates of nerve conduction measures was performed on data collected by the U.S. Centers for Disease Control. Nerve conduction velocity and amplitude were obtained for the median motor, median sensory, ulnar sensory, peroneal motor, and sural sensory nerves on 4,462 subjects. The magnitude of effect of skin temperature, height, body mass index, age, race, place of military service, smoking status, alcohol consumption, income, and EMG examiner was estimated for all 10 conduction outcomes. The major covariates were skin temperature, height, and examiner. Covariates with smaller but not unimportant effects on conduction outcomes were age, race, smoking status, and income. Alcohol consumption was associated with only small effects on conduction measures. These results provide an empirical basis for selection of variables to control in studies employing nerve conduction measures.