Intra and inter-raters reliability and agreement of stimulus electrodiagnostic tests with two different electrodes in sedated critically-ill patients

Objective: The aim of the present study was to verify the intra- and inter-rater reliability and agreement of the stimulus electrodiagnostic test (SET) measurements obtained by pen and square electrodes in the vastus lateralis and tibialis anterior muscles. Design: An intra- and inter-rater reliability and agreement study was performed for the SET by two independent raters. Two different sizes of cathode electrodes (1 cm(2) and 25 cm(2)) and two muscles were assessed (tibialis anterior and vastus lateralis). Results: Chronaxie did not change according to the different electrodes. A high intra-rater reliability (0.72 <= r <= 0.88) was detected independently of the electrode and muscle assessed. Moreover, moderate and almost perfect agreements (0.51 <= Kappa <= 1.00) were detected on intra-rater assessment. Similar correlations (0.74 <= r <= 0.79) were found for intra-rater reliability. However, dissimilar inter-rater agreement was detected: Kappa <= 0.40 for tibialis anterior and Kappa = 1.00 for vastus lateralis. Conclusion: The SET presented high reliability and moderate agreement in intra-rater evaluations. A fair agreement was found in the inter-rater assessment of the tibialis anterior. Evaluations performed with different electrode sizes did not influence the results. Therefore, the SET should be performed by a unique rater in test retest situations.