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 cm² and 25 cm²) 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.