Covariates of human peripheral nerve function: II. Vibrotactile and thermal thresholds.

A systematic investigation of covariates of quantitative sensory thresholds was performed on data collected by the U.S. Centers for Disease Control. Vibrotactile and thermal sensory thresholds were obtained from the index finger and great toe of 4,462 male Vietnam-era veterans. The magnitude of effect of skin temperature, height, body mass index, age, race, place of military service, smoking status, alcohol consumption, income, and examiner was estimated for the four outcomes. The major covariates of finger and toe vibrotactile threshold were age, height, body mass index, and examiner. The major covariates of toe thermal threshold were height, income, and examiner, and of finger thermal threshold were age, income, examiner, race, and smoking status. Alcohol consumption had only small effects on vibrotactile thresholds and essentially no effect on thermal thresholds. These results provide an empirical basis for selecting variables to control in studies employing vibrotactile and thermal threshold measures.