Reliability of nerve conduction studies among active workers

Nerve conduction studies play an important role in clinical practice and re search. Given their widespread use, reliability of tests merits careful att ention. We assessed interexaminer and intraexaminer reliability of median a nd ulnar sensory nerve measures of amplitude, onset latency, and peak laten cy. in a two-phase cross-sectional study, two examiners tested 158 workers. Reliability was assessed with intraclass correlations (ICC) and kappa stat istics. 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 th e worst reliability. The median-ulnar peak latency difference was a particu larly stable measure (ICC range, 0.79 to 0.92). The median-ulnar peak laten cy difference had high interexaminer reliability (kappa range, 0.71 to 0.79 ) for normal tests defined by cut points of 0.8 ms and 0.5 ms. Intraexamine r reliability was higher with the 0.8-ms cut point (kappa = 0.90 and kappa = 0.85 for examiners 1 and 2, respectively). Rather than absolute cut point s to describe normality, a more rational interpretation of results can be m ade with ordered categories or continuous measures. (C) 1999 John Wiley & S ons, Inc.